diff --git a/samples/BindingDemo/MainWindow.xaml b/samples/BindingDemo/MainWindow.xaml
index a69fb75742c..95713dc22fe 100644
--- a/samples/BindingDemo/MainWindow.xaml
+++ b/samples/BindingDemo/MainWindow.xaml
@@ -18,18 +18,18 @@
     <TabItem Header="Basic">
       <StackPanel Orientation="Vertical">
         <StackPanel Orientation="Horizontal">
-          <StackPanel Margin="18" Gap="4" Width="200">
+          <StackPanel Margin="18" Spacing="4" Width="200">
             <TextBlock FontSize="16" Text="Simple Bindings"/>
             <TextBox Watermark="Two Way" UseFloatingWatermark="True" Text="{Binding Path=StringValue}" Name="first"/>
             <TextBox Watermark="One Way" UseFloatingWatermark="True" Text="{Binding Path=StringValue, Mode=OneWay}"/>
             <TextBox Watermark="One Time" UseFloatingWatermark="True" Text="{Binding Path=StringValue, Mode=OneTime}"/>
           </StackPanel>
-          <StackPanel Margin="18" Gap="4" Width="200">
+          <StackPanel Margin="18" Spacing="4" Width="200">
             <TextBlock FontSize="16" Text="Collection Bindings"/>
             <TextBox Watermark="Items[1].StringValue" UseFloatingWatermark="True" Text="{Binding Path=Items[1].StringValue}"/>
             <Button Command="{Binding ShuffleItems}">Shuffle</Button>
           </StackPanel>
-          <StackPanel Margin="18" Gap="4" Width="200">
+          <StackPanel Margin="18" Spacing="4" Width="200">
             <TextBlock FontSize="16" Text="Negated Bindings"/>
             <TextBox Watermark="Boolean String" UseFloatingWatermark="True" Text="{Binding Path=BooleanString}"/>
             <CheckBox IsChecked="{Binding !BooleanString}">!BooleanString</CheckBox>
@@ -37,13 +37,13 @@
           </StackPanel>
         </StackPanel>
         <StackPanel Orientation="Horizontal">
-          <StackPanel Margin="18" Gap="4" Width="200" HorizontalAlignment="Left">
+          <StackPanel Margin="18" Spacing="4" Width="200" HorizontalAlignment="Left">
             <TextBlock FontSize="16" Text="Numeric Bindings"/>
             <TextBox Watermark="Double" UseFloatingWatermark="True" Text="{Binding Path=DoubleValue, Mode=TwoWay}"/>
             <TextBlock Text="{Binding Path=DoubleValue}"/>
             <ProgressBar Maximum="10" Value="{Binding DoubleValue}"/>
           </StackPanel>
-          <StackPanel Margin="18" Gap="4" Width="200" HorizontalAlignment="Left">
+          <StackPanel Margin="18" Spacing="4" Width="200" HorizontalAlignment="Left">
             <TextBlock FontSize="16" Text="Binding Sources"/>
             <TextBox Watermark="Value of first TextBox" UseFloatingWatermark="True" 
                      Text="{Binding #first.Text, Mode=TwoWay}"/>
@@ -52,7 +52,7 @@
             <TextBox Watermark="Value of SharedItem.StringValue (duplicate)" UseFloatingWatermark="True"
                      Text="{Binding StringValue, Source={StaticResource SharedItem}, Mode=TwoWay}"/>
           </StackPanel>
-          <StackPanel Margin="18" Gap="4" Width="200" HorizontalAlignment="Left">
+          <StackPanel Margin="18" Spacing="4" Width="200" HorizontalAlignment="Left">
             <TextBlock FontSize="16" Text="Scheduler"/>
             <TextBox Watermark="Background Thread" Text="{Binding CurrentTime, Mode=OneWay}"/>
             <TextBlock FontSize="16" Text="Stream Operator"/>
@@ -68,11 +68,11 @@
             <TextBlock Text="{Binding StringValue}"/>
           </DataTemplate>
         </StackPanel.DataTemplates>
-        <StackPanel Margin="18" Gap="4" Width="200">
+        <StackPanel Margin="18" Spacing="4" Width="200">
           <TextBlock FontSize="16" Text="Multiple"/>
           <ListBox Items="{Binding Items}" SelectionMode="Multiple" SelectedItems="{Binding SelectedItems}"/>
         </StackPanel>
-        <StackPanel Margin="18" Gap="4" Width="200">
+        <StackPanel Margin="18" Spacing="4" Width="200">
           <TextBlock FontSize="16" Text="Multiple"/>
           <ListBox Items="{Binding Items}" SelectionMode="Multiple" SelectedItems="{Binding SelectedItems}"/>
         </StackPanel>
@@ -87,16 +87,16 @@
     </TabItem>
     <TabItem Header="Property Validation">
       <StackPanel Orientation="Horizontal">
-        <StackPanel Margin="18" Gap="4" MinWidth="200" DataContext="{Binding ExceptionDataValidation}">
+        <StackPanel Margin="18" Spacing="4" MinWidth="200" DataContext="{Binding ExceptionDataValidation}">
           <TextBlock FontSize="16" Text="Exception Validation"/>
           <TextBox Watermark="Less Than 10" UseFloatingWatermark="True" Text="{Binding Path=LessThan10}"/>
         </StackPanel>
-        <StackPanel Margin="18" Gap="4" MinWidth="200" DataContext="{Binding IndeiDataValidation}">
+        <StackPanel Margin="18" Spacing="4" MinWidth="200" DataContext="{Binding IndeiDataValidation}">
           <TextBlock FontSize="16" Text="INotifyDataErrorInfo Validation"/>
           <TextBox Watermark="Maximum" UseFloatingWatermark="True" Text="{Binding Path=Maximum}"/>
           <TextBox Watermark="Value" UseFloatingWatermark="True" Text="{Binding Path=Value}"/>
         </StackPanel>
-        <StackPanel Margin="18" Gap="4" MinWidth="200" DataContext="{Binding DataAnnotationsValidation}">
+        <StackPanel Margin="18" Spacing="4" MinWidth="200" DataContext="{Binding DataAnnotationsValidation}">
           <TextBlock FontSize="16" Text="Data Annotations Validation"/>
           <TextBox Watermark="Phone #" UseFloatingWatermark="True" Text="{Binding PhoneNumber}"/>
           <TextBox Watermark="Less Than 10" UseFloatingWatermark="True" Text="{Binding Path=LessThan10}"/>
@@ -104,7 +104,7 @@
       </StackPanel>
     </TabItem>
     <TabItem Header="Commands">
-      <StackPanel Margin="18" Gap="4" Width="200">
+      <StackPanel Margin="18" Spacing="4" Width="200">
         <Button Content="Button" Command="{Binding StringValueCommand}" CommandParameter="Button"/>
         <ToggleButton Content="ToggleButton" IsChecked="{Binding BooleanFlag, Mode=OneWay}" Command="{Binding StringValueCommand}" CommandParameter="ToggleButton"/>
         <CheckBox Content="CheckBox" IsChecked="{Binding !BooleanFlag, Mode=OneWay}" Command="{Binding StringValueCommand}" CommandParameter="CheckBox"/>
@@ -114,4 +114,4 @@
       </StackPanel>
     </TabItem>
   </TabControl>
-</Window>
\ No newline at end of file
+</Window>
diff --git a/samples/ControlCatalog/Pages/AutoCompleteBoxPage.xaml b/samples/ControlCatalog/Pages/AutoCompleteBoxPage.xaml
index 943fadf100b..28bdc7ac71a 100644
--- a/samples/ControlCatalog/Pages/AutoCompleteBoxPage.xaml
+++ b/samples/ControlCatalog/Pages/AutoCompleteBoxPage.xaml
@@ -1,12 +1,12 @@
 <UserControl xmlns="https://github.com/avaloniaui">
-  <StackPanel Orientation="Vertical" Gap="4">
+  <StackPanel Orientation="Vertical" Spacing="4">
     <TextBlock Classes="h1">AutoCompleteBox</TextBlock>
     <TextBlock Classes="h2">A control into which the user can input text</TextBlock>
 
     <StackPanel Orientation="Horizontal"
               Margin="0,16,0,0"
               HorizontalAlignment="Center"
-              Gap="8">
+              Spacing="8">
       <StackPanel Orientation="Vertical">
         <TextBlock Text="MinimumPrefixLength: 1"/>
         <AutoCompleteBox Width="200"
@@ -56,4 +56,4 @@
       </StackPanel>
     </StackPanel>
   </StackPanel>
-</UserControl>
\ No newline at end of file
+</UserControl>
diff --git a/samples/ControlCatalog/Pages/BorderPage.xaml b/samples/ControlCatalog/Pages/BorderPage.xaml
index a81bd13ddd6..09f591d59d3 100644
--- a/samples/ControlCatalog/Pages/BorderPage.xaml
+++ b/samples/ControlCatalog/Pages/BorderPage.xaml
@@ -1,12 +1,12 @@
 <UserControl xmlns="https://github.com/avaloniaui">
-  <StackPanel Orientation="Vertical" Gap="4">
+  <StackPanel Orientation="Vertical" Spacing="4">
     <TextBlock Classes="h1">Border</TextBlock>
     <TextBlock Classes="h2">A control which decorates a child with a border and background</TextBlock>
 
     <StackPanel Orientation="Vertical"
                 Margin="0,16,0,0"
                 HorizontalAlignment="Center"
-                Gap="16">
+                Spacing="16">
       <Border BorderBrush="{DynamicResource ThemeAccentBrush}" BorderThickness="2" Padding="16">
         <TextBlock>Border</TextBlock>
       </Border>
@@ -29,4 +29,4 @@
       </Border>
     </StackPanel>    
   </StackPanel>
-</UserControl>
\ No newline at end of file
+</UserControl>
diff --git a/samples/ControlCatalog/Pages/ButtonPage.xaml b/samples/ControlCatalog/Pages/ButtonPage.xaml
index b5335ff15e5..38757148ab2 100644
--- a/samples/ControlCatalog/Pages/ButtonPage.xaml
+++ b/samples/ControlCatalog/Pages/ButtonPage.xaml
@@ -1,14 +1,14 @@
 <UserControl xmlns="https://github.com/avaloniaui"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
-  <StackPanel Orientation="Vertical" Gap="4">
+  <StackPanel Orientation="Vertical" Spacing="4">
     <TextBlock Classes="h1">Button</TextBlock>
     <TextBlock Classes="h2">A button control</TextBlock>
 
     <StackPanel Orientation="Horizontal"
                 Margin="0,16,0,0"
                 HorizontalAlignment="Center"
-                Gap="16">
-      <StackPanel Orientation="Vertical" Gap="8" Width="150">
+                Spacing="16">
+      <StackPanel Orientation="Vertical" Spacing="8" Width="150">
         <Button>Button</Button>
         <Button Foreground="White">Foreground</Button>
         <Button Background="{DynamicResource ThemeAccentBrush}">Background</Button>
@@ -25,7 +25,7 @@
         </Button>
       </StackPanel>
 
-      <StackPanel Orientation="Vertical" Gap="8" Width="150">
+      <StackPanel Orientation="Vertical" Spacing="8" Width="150">
         <Button BorderThickness="0">No Border</Button>
         <Button BorderBrush="{DynamicResource ThemeAccentBrush}">Border Color</Button>
         <Button BorderBrush="{DynamicResource ThemeAccentBrush}" BorderThickness="4">Thick Border</Button>
@@ -33,4 +33,4 @@
       </StackPanel>
     </StackPanel>    
   </StackPanel>
-</UserControl>
\ No newline at end of file
+</UserControl>
diff --git a/samples/ControlCatalog/Pages/ButtonSpinnerPage.xaml b/samples/ControlCatalog/Pages/ButtonSpinnerPage.xaml
index 1797fb48bcc..fba15f6e772 100644
--- a/samples/ControlCatalog/Pages/ButtonSpinnerPage.xaml
+++ b/samples/ControlCatalog/Pages/ButtonSpinnerPage.xaml
@@ -1,11 +1,11 @@
 <UserControl xmlns="https://github.com/avaloniaui"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
 
-  <StackPanel Orientation="Vertical" Gap="4">
+  <StackPanel Orientation="Vertical" Spacing="4">
     <TextBlock Classes="h1">ButtonSpinner</TextBlock>
     <TextBlock Classes="h2">The ButtonSpinner control allows you to add button spinners to any element and then respond to the Spin event to manipulate that element.</TextBlock>
 
-    <StackPanel Orientation="Vertical" Gap="8" Width="200" Margin="0,20,0,0">
+    <StackPanel Orientation="Vertical" Spacing="8" Width="200" Margin="0,20,0,0">
       <CheckBox Name="allowSpinCheck" IsChecked="True">AllowSpin</CheckBox>
       <CheckBox Name="showSpinCheck" IsChecked="True">ShowButtonSpinner</CheckBox>
       <ButtonSpinner Spin="OnSpin" Height="30"
@@ -21,4 +21,4 @@
     </StackPanel>
   </StackPanel>
 
-</UserControl>
\ No newline at end of file
+</UserControl>
diff --git a/samples/ControlCatalog/Pages/CalendarPage.xaml b/samples/ControlCatalog/Pages/CalendarPage.xaml
index a433fd1add9..c47fd766fb6 100644
--- a/samples/ControlCatalog/Pages/CalendarPage.xaml
+++ b/samples/ControlCatalog/Pages/CalendarPage.xaml
@@ -1,13 +1,13 @@
 <UserControl xmlns="https://github.com/avaloniaui"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
-  <StackPanel Orientation="Vertical" Gap="4">
+  <StackPanel Orientation="Vertical" Spacing="4">
     <TextBlock Classes="h1">Calendar</TextBlock>
     <TextBlock Classes="h2">A calendar control for selecting dates</TextBlock>
         
     <StackPanel Orientation="Horizontal"
                 Margin="0,16,0,0"
                 HorizontalAlignment="Center"
-                Gap="16">
+                Spacing="16">
       <StackPanel Orientation="Vertical">
         <TextBlock Text="SelectionMode: None"/>
         <Calendar SelectionMode="None"
@@ -44,4 +44,4 @@
       
     </StackPanel> 
   </StackPanel>
-</UserControl>
\ No newline at end of file
+</UserControl>
diff --git a/samples/ControlCatalog/Pages/CanvasPage.xaml b/samples/ControlCatalog/Pages/CanvasPage.xaml
index f934f57c228..10a38895a2b 100644
--- a/samples/ControlCatalog/Pages/CanvasPage.xaml
+++ b/samples/ControlCatalog/Pages/CanvasPage.xaml
@@ -1,5 +1,5 @@
 <UserControl xmlns="https://github.com/avaloniaui">
-  <StackPanel Orientation="Vertical" Gap="4">
+  <StackPanel Orientation="Vertical" Spacing="4">
     <TextBlock Classes="h1">Canvas</TextBlock>
     <TextBlock Classes="h2">A panel which lays out its children by explicit coordinates</TextBlock>
     <Canvas Background="Yellow" Width="300" Height="400">
@@ -31,4 +31,4 @@
       <Polyline Points="0,0 65,0 78,-26 91,39 104,-39 117,13 130,0 195,0" Stroke="Brown" Canvas.Left="30" Canvas.Top="350"/>
     </Canvas>
   </StackPanel>
-</UserControl>
\ No newline at end of file
+</UserControl>
diff --git a/samples/ControlCatalog/Pages/CarouselPage.xaml b/samples/ControlCatalog/Pages/CarouselPage.xaml
index 3468b71fd82..cf9b13c00c5 100644
--- a/samples/ControlCatalog/Pages/CarouselPage.xaml
+++ b/samples/ControlCatalog/Pages/CarouselPage.xaml
@@ -1,9 +1,9 @@
 <UserControl xmlns="https://github.com/avaloniaui">
-  <StackPanel Orientation="Vertical" Gap="4">
+  <StackPanel Orientation="Vertical" Spacing="4">
     <TextBlock Classes="h1">Carousel</TextBlock>
     <TextBlock Classes="h2">An items control that displays its items as pages that fill the control.</TextBlock>
 
-    <StackPanel Orientation="Horizontal" HorizontalAlignment="Center" Margin="0 16 0 0" Gap="8">
+    <StackPanel Orientation="Horizontal" HorizontalAlignment="Center" Margin="0 16 0 0" Spacing="8">
       <Button Name="left" VerticalAlignment="Center" Padding="20">
         <Path Data="M20,11V13H8L13.5,18.5L12.08,19.92L4.16,12L12.08,4.08L13.5,5.5L8,11H20Z" Fill="Black"/>
       </Button>
@@ -20,7 +20,7 @@
       </Button>
     </StackPanel>
 
-    <StackPanel Orientation="Horizontal" Gap="4">
+    <StackPanel Orientation="Horizontal" Spacing="4">
       <TextBlock VerticalAlignment="Center">Transition</TextBlock>
       <DropDown Name="transition" SelectedIndex="1" VerticalAlignment="Center">
         <DropDownItem>None</DropDownItem>
@@ -29,7 +29,7 @@
       </DropDown>
     </StackPanel>
 
-    <StackPanel Orientation="Horizontal" Gap="4">
+    <StackPanel Orientation="Horizontal" Spacing="4">
       <TextBlock VerticalAlignment="Center">Orientation</TextBlock>
       <DropDown Name="orientation" SelectedIndex="1" VerticalAlignment="Center">
         <DropDownItem>Horizontal</DropDownItem>
@@ -38,4 +38,4 @@
     </StackPanel>
     
   </StackPanel>
-</UserControl>
\ No newline at end of file
+</UserControl>
diff --git a/samples/ControlCatalog/Pages/CheckBoxPage.xaml b/samples/ControlCatalog/Pages/CheckBoxPage.xaml
index a00b3a7bef6..154a6254a4d 100644
--- a/samples/ControlCatalog/Pages/CheckBoxPage.xaml
+++ b/samples/ControlCatalog/Pages/CheckBoxPage.xaml
@@ -1,15 +1,15 @@
 <UserControl xmlns="https://github.com/avaloniaui"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
-  <StackPanel Orientation="Vertical" Gap="4">
+  <StackPanel Orientation="Vertical" Spacing="4">
     <TextBlock Classes="h1">CheckBox</TextBlock>
     <TextBlock Classes="h2">A check box control</TextBlock>
 
     <StackPanel Orientation="Horizontal"
                 Margin="0,16,0,0"
                 HorizontalAlignment="Center"
-                Gap="16">
+                Spacing="16">
       <StackPanel Orientation="Vertical"
-                  Gap="16">
+                  Spacing="16">
         <CheckBox>Unchecked</CheckBox>
         <CheckBox IsChecked="True">Checked</CheckBox>
         <CheckBox IsChecked="{x:Null}">Indeterminate</CheckBox>
@@ -17,7 +17,7 @@
       </StackPanel>
       <StackPanel Orientation="Vertical"
                   HorizontalAlignment="Center"
-                  Gap="16">
+                  Spacing="16">
         <CheckBox IsChecked="False" IsThreeState="True">Three State: Unchecked</CheckBox>
         <CheckBox IsChecked="True" IsThreeState="True">Three State: Checked</CheckBox>
         <CheckBox IsChecked="{x:Null}" IsThreeState="True">Three State: Indeterminate</CheckBox>
@@ -25,4 +25,4 @@
       </StackPanel>
     </StackPanel>
   </StackPanel>
-</UserControl>
\ No newline at end of file
+</UserControl>
diff --git a/samples/ControlCatalog/Pages/ContextMenuPage.xaml b/samples/ControlCatalog/Pages/ContextMenuPage.xaml
index 3af823befce..37eeaeb2ac9 100644
--- a/samples/ControlCatalog/Pages/ContextMenuPage.xaml
+++ b/samples/ControlCatalog/Pages/ContextMenuPage.xaml
@@ -1,12 +1,12 @@
 <UserControl xmlns="https://github.com/avaloniaui">
-    <StackPanel Orientation="Vertical" Gap="4">
+    <StackPanel Orientation="Vertical" Spacing="4">
         <TextBlock Classes="h1">Context Menu</TextBlock>
         <TextBlock Classes="h2">A right click menu that can be applied to any control.</TextBlock>
 
         <StackPanel Orientation="Horizontal"
               Margin="0,16,0,0"
               HorizontalAlignment="Center"
-              Gap="16">
+              Spacing="16">
             <Border Background="{DynamicResource ThemeAccentBrush}"
               Padding="48,48,48,48">
                 <Border.ContextMenu>
@@ -33,4 +33,4 @@
             </Border>
         </StackPanel>
     </StackPanel>
-</UserControl>
\ No newline at end of file
+</UserControl>
diff --git a/samples/ControlCatalog/Pages/DatePickerPage.xaml b/samples/ControlCatalog/Pages/DatePickerPage.xaml
index 92cfa7e1782..2c34460fcee 100644
--- a/samples/ControlCatalog/Pages/DatePickerPage.xaml
+++ b/samples/ControlCatalog/Pages/DatePickerPage.xaml
@@ -1,13 +1,13 @@
 <UserControl xmlns="https://github.com/avaloniaui"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
-  <StackPanel Orientation="Vertical" Gap="4">
+  <StackPanel Orientation="Vertical" Spacing="4">
     <TextBlock Classes="h1">DatePicker</TextBlock>
     <TextBlock Classes="h2">A control for selecting dates with a calendar drop-down</TextBlock>
         
     <StackPanel Orientation="Horizontal"
                 Margin="0,16,0,0"
                 HorizontalAlignment="Center"
-                Gap="16">
+                Spacing="16">
       <StackPanel Orientation="Vertical"
                   Width="200">
         <TextBlock Text="SelectedDateFormat: Short"/>
@@ -43,4 +43,4 @@
 
     </StackPanel> 
   </StackPanel>
-</UserControl>
\ No newline at end of file
+</UserControl>
diff --git a/samples/ControlCatalog/Pages/DialogsPage.xaml b/samples/ControlCatalog/Pages/DialogsPage.xaml
index c3e94356302..710d791f3a3 100644
--- a/samples/ControlCatalog/Pages/DialogsPage.xaml
+++ b/samples/ControlCatalog/Pages/DialogsPage.xaml
@@ -1,5 +1,5 @@
 <UserControl xmlns="https://github.com/avaloniaui">
-  <StackPanel Orientation="Vertical" Gap="4" Margin="4">
+  <StackPanel Orientation="Vertical" Spacing="4" Margin="4">
       <Button Name="OpenFile">Open File</Button>
       <Button Name="SaveFile">Save File</Button>
       <Button Name="SelectFolder">Select Folder</Button>
@@ -9,4 +9,4 @@
       </StackPanel>
       <Button Name="DecoratedWindow">Decorated window</Button>
   </StackPanel>
-</UserControl>
\ No newline at end of file
+</UserControl>
diff --git a/samples/ControlCatalog/Pages/DragAndDropPage.xaml b/samples/ControlCatalog/Pages/DragAndDropPage.xaml
index af679d2f9aa..1f3cd3ff71c 100644
--- a/samples/ControlCatalog/Pages/DragAndDropPage.xaml
+++ b/samples/ControlCatalog/Pages/DragAndDropPage.xaml
@@ -1,12 +1,12 @@
 <UserControl xmlns="https://github.com/avaloniaui">
-    <StackPanel Orientation="Vertical" Gap="4">
+    <StackPanel Orientation="Vertical" Spacing="4">
         <TextBlock Classes="h1">Drag+Drop</TextBlock>
         <TextBlock Classes="h2">Example of Drag+Drop capabilities</TextBlock>
 
         <StackPanel Orientation="Horizontal"
                 Margin="0,16,0,0"
                 HorizontalAlignment="Center"
-                Gap="16">
+                Spacing="16">
             <Border BorderBrush="{DynamicResource ThemeAccentBrush}" BorderThickness="2" Padding="16" Name="DragMe">
                 <TextBlock Name="DragState">Drag Me</TextBlock>
             </Border>
@@ -16,4 +16,4 @@
             </Border>
         </StackPanel>
     </StackPanel>
-</UserControl>
\ No newline at end of file
+</UserControl>
diff --git a/samples/ControlCatalog/Pages/DropDownPage.xaml b/samples/ControlCatalog/Pages/DropDownPage.xaml
index 0a7a88e3317..5e2a3102e7d 100644
--- a/samples/ControlCatalog/Pages/DropDownPage.xaml
+++ b/samples/ControlCatalog/Pages/DropDownPage.xaml
@@ -1,9 +1,9 @@
 <UserControl xmlns="https://github.com/avaloniaui">
-  <StackPanel Orientation="Vertical" Gap="4">
+  <StackPanel Orientation="Vertical" Spacing="4">
     <TextBlock Classes="h1">DropDown</TextBlock>
     <TextBlock Classes="h2">A drop-down list.</TextBlock>
 
-    <StackPanel Orientation="Horizontal" HorizontalAlignment="Center" Margin="0 16 0 0" Gap="8">
+    <StackPanel Orientation="Horizontal" HorizontalAlignment="Center" Margin="0 16 0 0" Spacing="8">
       <DropDown SelectedIndex="0">
         <DropDownItem>Inline Items</DropDownItem>
         <DropDownItem>Inline Item 2</DropDownItem>
@@ -28,4 +28,4 @@
     </StackPanel>
 
   </StackPanel>
-</UserControl>
\ No newline at end of file
+</UserControl>
diff --git a/samples/ControlCatalog/Pages/ExpanderPage.xaml b/samples/ControlCatalog/Pages/ExpanderPage.xaml
index e32fa1caf15..91440929f5a 100644
--- a/samples/ControlCatalog/Pages/ExpanderPage.xaml
+++ b/samples/ControlCatalog/Pages/ExpanderPage.xaml
@@ -1,12 +1,12 @@
 <UserControl xmlns="https://github.com/avaloniaui">
-  <StackPanel Orientation="Vertical" Gap="4">
+  <StackPanel Orientation="Vertical" Spacing="4">
     <TextBlock Classes="h1">Expander</TextBlock>
     <TextBlock Classes="h2">Expands to show nested content</TextBlock>
 
     <StackPanel Orientation="Vertical"
                 Margin="0,16,0,0"
                 HorizontalAlignment="Center"
-                Gap="16">
+                Spacing="16">
       <Expander Header="Expand Up" ExpandDirection="Up">
         <StackPanel>
           <TextBlock>Expanded content</TextBlock>
@@ -29,4 +29,4 @@
       </Expander>
     </StackPanel>    
   </StackPanel>
-</UserControl>
\ No newline at end of file
+</UserControl>
diff --git a/samples/ControlCatalog/Pages/ImagePage.xaml b/samples/ControlCatalog/Pages/ImagePage.xaml
index dc93808f27b..78fbf90192d 100644
--- a/samples/ControlCatalog/Pages/ImagePage.xaml
+++ b/samples/ControlCatalog/Pages/ImagePage.xaml
@@ -1,12 +1,12 @@
 <UserControl xmlns="https://github.com/avaloniaui">
-  <StackPanel Orientation="Vertical" Gap="4">
+  <StackPanel Orientation="Vertical" Spacing="4">
     <TextBlock Classes="h1">Image</TextBlock>
     <TextBlock Classes="h2">Displays an image</TextBlock>
 
     <StackPanel Orientation="Horizontal"
                 Margin="0,16,0,0"
                 HorizontalAlignment="Center"
-                Gap="16">
+                Spacing="16">
       <StackPanel Orientation="Vertical">
         <TextBlock>No Stretch</TextBlock>
         <Image Source="resm:ControlCatalog.Assets.delicate-arch-896885_640.jpg"
diff --git a/samples/ControlCatalog/Pages/MenuPage.xaml b/samples/ControlCatalog/Pages/MenuPage.xaml
index 36adcf1b8f4..296cfa87047 100644
--- a/samples/ControlCatalog/Pages/MenuPage.xaml
+++ b/samples/ControlCatalog/Pages/MenuPage.xaml
@@ -1,12 +1,12 @@
 <UserControl xmlns="https://github.com/avaloniaui">
-  <StackPanel Orientation="Vertical" Gap="4">
+  <StackPanel Orientation="Vertical" Spacing="4">
     <TextBlock Classes="h1">Menu</TextBlock>
     <TextBlock Classes="h2">A window menu</TextBlock>
 
         <StackPanel Orientation="Horizontal"
               Margin="0,16,0,0"
               HorizontalAlignment="Center"
-              Gap="16">
+              Spacing="16">
             <Menu>
                 <MenuItem Header="_First">
                     <MenuItem Header="Standard _Menu Item"/>
diff --git a/samples/ControlCatalog/Pages/NumericUpDownPage.xaml b/samples/ControlCatalog/Pages/NumericUpDownPage.xaml
index a5c911f47d7..305bcd177c0 100644
--- a/samples/ControlCatalog/Pages/NumericUpDownPage.xaml
+++ b/samples/ControlCatalog/Pages/NumericUpDownPage.xaml
@@ -1,6 +1,6 @@
 <UserControl xmlns="https://github.com/avaloniaui"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
-  <StackPanel Orientation="Vertical" Gap="4">
+  <StackPanel Orientation="Vertical" Spacing="4">
     <TextBlock Margin="2" Classes="h1">Numeric up-down control</TextBlock>
     <TextBlock Margin="2" Classes="h2" TextWrapping="Wrap">Numeric up-down control provides a TextBox with button spinners that allow incrementing and decrementing numeric values by using the spinner buttons, keyboard up/down arrows, or mouse wheel.</TextBlock>
 
@@ -26,7 +26,7 @@
                   VerticalAlignment="Center" Margin="2">
           <DropDown.ItemTemplate>
             <DataTemplate>
-              <StackPanel Orientation="Horizontal" Gap="2">
+              <StackPanel Orientation="Horizontal" Spacing="2">
                 <TextBlock Text="{Binding Name}"/>
                 <TextBlock Text="-"/>
                 <TextBlock Text="{Binding Value}"/>
@@ -69,7 +69,7 @@
       </Grid>
     </Grid>
 
-    <StackPanel Margin="2,10,2,2" Orientation="Horizontal" Gap="10">
+    <StackPanel Margin="2,10,2,2" Orientation="Horizontal" Spacing="10">
       <TextBlock FontSize="14" FontWeight="Bold" VerticalAlignment="Center">Usage of NumericUpDown:</TextBlock>
       <NumericUpDown Name="upDown" Minimum="0" Maximum="10" Increment="0.5"
                      CultureInfo="en-US" VerticalAlignment="Center" Height="25" Width="100"
diff --git a/samples/ControlCatalog/Pages/ProgressBarPage.xaml b/samples/ControlCatalog/Pages/ProgressBarPage.xaml
index bf40e686305..a40aa0ea9ae 100644
--- a/samples/ControlCatalog/Pages/ProgressBarPage.xaml
+++ b/samples/ControlCatalog/Pages/ProgressBarPage.xaml
@@ -1,5 +1,5 @@
 <UserControl xmlns="https://github.com/avaloniaui">
-  <StackPanel Orientation="Vertical" Gap="4">
+  <StackPanel Orientation="Vertical" Spacing="4">
     <TextBlock Classes="h1">ProgressBar</TextBlock>
     <TextBlock Classes="h2">A progress bar control</TextBlock>
 
@@ -7,8 +7,8 @@
       <StackPanel Orientation="Horizontal"
                   Margin="0,16,0,0"
                   HorizontalAlignment="Center"
-                  Gap="16">
-        <StackPanel Gap="16">
+                  Spacing="16">
+        <StackPanel Spacing="16">
           <ProgressBar Value="{Binding #hprogress.Value}" />
           <ProgressBar IsIndeterminate="True"/>
         </StackPanel>
diff --git a/samples/ControlCatalog/Pages/RadioButtonPage.xaml b/samples/ControlCatalog/Pages/RadioButtonPage.xaml
index d382b94f2c1..0882817a9a5 100644
--- a/samples/ControlCatalog/Pages/RadioButtonPage.xaml
+++ b/samples/ControlCatalog/Pages/RadioButtonPage.xaml
@@ -1,22 +1,22 @@
 <UserControl xmlns="https://github.com/avaloniaui"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
-  <StackPanel Orientation="Vertical" Gap="4">
+  <StackPanel Orientation="Vertical" Spacing="4">
     <TextBlock Classes="h1">RadioButton</TextBlock>
     <TextBlock Classes="h2">Allows the selection of a single option of many</TextBlock>
 
     <StackPanel Orientation="Horizontal"
                 Margin="0,16,0,0"
                 HorizontalAlignment="Center"
-                Gap="16">
+                Spacing="16">
       <StackPanel Orientation="Vertical"
-                  Gap="16">
+                  Spacing="16">
         <RadioButton IsChecked="True">Option 1</RadioButton>
         <RadioButton>Option 2</RadioButton>
         <RadioButton IsChecked="{x:Null}">Option 3</RadioButton>
         <RadioButton IsEnabled="False">Disabled</RadioButton>
       </StackPanel>
       <StackPanel Orientation="Vertical"
-                  Gap="16">
+                  Spacing="16">
         <RadioButton IsChecked="True" IsThreeState="True">Three States: Option 1</RadioButton>
         <RadioButton IsChecked="False" IsThreeState="True">Three States: Option 2</RadioButton>
         <RadioButton IsChecked="{x:Null}" IsThreeState="True">Three States: Option 3</RadioButton>
diff --git a/samples/ControlCatalog/Pages/SliderPage.xaml b/samples/ControlCatalog/Pages/SliderPage.xaml
index e43968cb8e1..6db71b5fcc7 100644
--- a/samples/ControlCatalog/Pages/SliderPage.xaml
+++ b/samples/ControlCatalog/Pages/SliderPage.xaml
@@ -1,9 +1,9 @@
 <UserControl xmlns="https://github.com/avaloniaui">
-  <StackPanel Orientation="Vertical" Gap="4">
+  <StackPanel Orientation="Vertical" Spacing="4">
     <TextBlock Classes="h1">Slider</TextBlock>
     <TextBlock Classes="h2">A control that lets the user select from a range of values by moving a Thumb control along a Track.</TextBlock>
 
-    <StackPanel Orientation="Horizontal" HorizontalAlignment="Center" Margin="0 16 0 0" Gap="16">
+    <StackPanel Orientation="Horizontal" HorizontalAlignment="Center" Margin="0 16 0 0" Spacing="16">
       <Slider Value="0"
               Minimum="0"
               Maximum="100"
diff --git a/samples/ControlCatalog/Pages/TextBoxPage.xaml b/samples/ControlCatalog/Pages/TextBoxPage.xaml
index a7175186557..5f94e15ceca 100644
--- a/samples/ControlCatalog/Pages/TextBoxPage.xaml
+++ b/samples/ControlCatalog/Pages/TextBoxPage.xaml
@@ -1,13 +1,13 @@
 <UserControl xmlns="https://github.com/avaloniaui">
-  <StackPanel Orientation="Vertical" Gap="4">
+  <StackPanel Orientation="Vertical" Spacing="4">
     <TextBlock Classes="h1">TextBox</TextBlock>
     <TextBlock Classes="h2">A control into which the user can input text</TextBlock>
 
     <StackPanel Orientation="Horizontal"
               Margin="0,16,0,0"
               HorizontalAlignment="Center"
-              Gap="16">
-      <StackPanel Orientation="Vertical" Gap="8">
+              Spacing="16">
+      <StackPanel Orientation="Vertical" Spacing="8">
         <TextBox Text="Lorem ipsum dolor sit amet, consectetur adipiscing elit." Width="200" />
         <TextBox Watermark="ReadOnly" IsReadOnly="True" Text="This is read only"/>
         <TextBox Width="200" Watermark="Watermark" />
@@ -26,13 +26,13 @@
         <TextBox Width="200" Text="Right aligned text" TextAlignment="Right" />
       </StackPanel>
 
-      <StackPanel Orientation="Vertical" Gap="8">
+      <StackPanel Orientation="Vertical" Spacing="8">
         <TextBox AcceptsReturn="True" TextWrapping="Wrap" Width="200" Height="125"
                  Text="Multiline TextBox with TextWrapping.&#xD;&#xD;Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vivamus magna. Cras in mi at felis aliquet congue. Ut a est eget ligula molestie gravida. Curabitur massa. Donec eleifend, libero at sagittis mollis, tellus est malesuada tellus, at luctus turpis elit sit amet quam. Vivamus pretium ornare est." />
         <TextBox AcceptsReturn="True" Width="200" Height="125"
                  Text="Multiline TextBox with no TextWrapping.&#xD;&#xD;Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vivamus magna. Cras in mi at felis aliquet congue. Ut a est eget ligula molestie gravida. Curabitur massa. Donec eleifend, libero at sagittis mollis, tellus est malesuada tellus, at luctus turpis elit sit amet quam. Vivamus pretium ornare est." />
       </StackPanel>
-        <StackPanel Orientation="Vertical" Gap="8">
+        <StackPanel Orientation="Vertical" Spacing="8">
             <TextBox Width="200" Text="Custom font regular" FontWeight="Normal" FontStyle="Normal" FontFamily="resm:ControlCatalog.Assets.Fonts?assembly=ControlCatalog#Source Sans Pro"/>
                 <TextBox Width="200" Text="Custom font bold" FontWeight="Bold" FontStyle="Normal" FontFamily="resm:ControlCatalog.Assets.Fonts?assembly=ControlCatalog#Source Sans Pro"/>
                 <TextBox Width="200" Text="Custom font italic" FontWeight="Normal" FontStyle="Italic" FontFamily="resm:ControlCatalog.Assets.Fonts.SourceSansPro-Italic.ttf?assembly=ControlCatalog#Source Sans Pro"/>
diff --git a/samples/ControlCatalog/Pages/ToolTipPage.xaml b/samples/ControlCatalog/Pages/ToolTipPage.xaml
index aa7d60bd11a..ad832b9b82b 100644
--- a/samples/ControlCatalog/Pages/ToolTipPage.xaml
+++ b/samples/ControlCatalog/Pages/ToolTipPage.xaml
@@ -1,6 +1,6 @@
 <UserControl xmlns="https://github.com/avaloniaui">
     <StackPanel Orientation="Vertical"
-                Gap="4">
+                Spacing="4">
         <TextBlock Classes="h1">ToolTip</TextBlock>
         <TextBlock Classes="h2">A control which pops up a hint when a control is hovered</TextBlock>
 
diff --git a/samples/ControlCatalog/Pages/TreeViewPage.xaml b/samples/ControlCatalog/Pages/TreeViewPage.xaml
index 5806e58c272..1ab49dbb308 100644
--- a/samples/ControlCatalog/Pages/TreeViewPage.xaml
+++ b/samples/ControlCatalog/Pages/TreeViewPage.xaml
@@ -1,12 +1,12 @@
 <UserControl xmlns="https://github.com/avaloniaui">
-  <StackPanel Orientation="Vertical" Gap="4">
+  <StackPanel Orientation="Vertical" Spacing="4">
     <TextBlock Classes="h1">TreeView</TextBlock>
     <TextBlock Classes="h2">Displays a hierachical tree of data.</TextBlock>
 
     <StackPanel Orientation="Horizontal"
               Margin="0,16,0,0"
               HorizontalAlignment="Center"
-              Gap="16">
+              Spacing="16">
       <TreeView Items="{Binding}" Width="250" Height="350">
         <TreeView.ItemTemplate>
           <TreeDataTemplate ItemsSource="{Binding Children}">
diff --git a/samples/VirtualizationDemo/MainWindow.xaml b/samples/VirtualizationDemo/MainWindow.xaml
index eb94253d270..730b61ed547 100644
--- a/samples/VirtualizationDemo/MainWindow.xaml
+++ b/samples/VirtualizationDemo/MainWindow.xaml
@@ -6,7 +6,7 @@
         <StackPanel DockPanel.Dock="Right" 
                     Margin="16 0 0 0" 
                     MinWidth="150"
-                    Gap="4">
+                    Spacing="4">
             <DropDown Items="{Binding VirtualizationModes}"
                       SelectedItem="{Binding VirtualizationMode}"/>
             <DropDown Items="{Binding Orientations}"
diff --git a/src/Avalonia.Controls/StackPanel.cs b/src/Avalonia.Controls/StackPanel.cs
index d404e6913be..b0ccd8a3d1a 100644
--- a/src/Avalonia.Controls/StackPanel.cs
+++ b/src/Avalonia.Controls/StackPanel.cs
@@ -13,10 +13,10 @@ namespace Avalonia.Controls
     public class StackPanel : Panel, INavigableContainer
     {
         /// <summary>
-        /// Defines the <see cref="Gap"/> property.
+        /// Defines the <see cref="Spacing"/> property.
         /// </summary>
-        public static readonly StyledProperty<double> GapProperty =
-            AvaloniaProperty.Register<StackPanel, double>(nameof(Gap));
+        public static readonly StyledProperty<double> SpacingProperty =
+            AvaloniaProperty.Register<StackPanel, double>(nameof(Spacing));
 
         /// <summary>
         /// Defines the <see cref="Orientation"/> property.
@@ -29,17 +29,17 @@ public class StackPanel : Panel, INavigableContainer
         /// </summary>
         static StackPanel()
         {
-            AffectsMeasure(GapProperty);
+            AffectsMeasure(SpacingProperty);
             AffectsMeasure(OrientationProperty);
         }
 
         /// <summary>
-        /// Gets or sets the size of the gap to place between child controls.
+        /// Gets or sets the size of the spacing to place between child controls.
         /// </summary>
-        public double Gap
+        public double Spacing
         {
-            get { return GetValue(GapProperty); }
-            set { SetValue(GapProperty, value); }
+            get { return GetValue(SpacingProperty); }
+            set { SetValue(SpacingProperty, value); }
         }
 
         /// <summary>
@@ -152,7 +152,7 @@ protected override Size MeasureOverride(Size availableSize)
 
             double measuredWidth = 0;
             double measuredHeight = 0;
-            double gap = Gap;
+            double spacing = Spacing;
             bool hasVisibleChild = Children.Any(c => c.IsVisible);
 
             foreach (Control child in Children)
@@ -162,23 +162,23 @@ protected override Size MeasureOverride(Size availableSize)
 
                 if (Orientation == Orientation.Vertical)
                 {
-                    measuredHeight += size.Height + (child.IsVisible ? gap : 0);
+                    measuredHeight += size.Height + (child.IsVisible ? spacing : 0);
                     measuredWidth = Math.Max(measuredWidth, size.Width);
                 }
                 else
                 {
-                    measuredWidth += size.Width + (child.IsVisible ? gap : 0);   
+                    measuredWidth += size.Width + (child.IsVisible ? spacing : 0);   
                     measuredHeight = Math.Max(measuredHeight, size.Height);
                 }
             }
 
             if (Orientation == Orientation.Vertical)
             {
-                measuredHeight -= (hasVisibleChild ? gap : 0);
+                measuredHeight -= (hasVisibleChild ? spacing : 0);
             }
             else
             {
-                measuredWidth -= (hasVisibleChild ? gap : 0);
+                measuredWidth -= (hasVisibleChild ? spacing : 0);
             }
 
             return new Size(measuredWidth, measuredHeight);
@@ -194,7 +194,7 @@ protected override Size ArrangeOverride(Size finalSize)
             var orientation = Orientation;
             double arrangedWidth = finalSize.Width;
             double arrangedHeight = finalSize.Height;
-            double gap = Gap;
+            double spacing = Spacing;
             bool hasVisibleChild = Children.Any(c => c.IsVisible);
 
             if (Orientation == Orientation.Vertical)
@@ -217,25 +217,25 @@ protected override Size ArrangeOverride(Size finalSize)
                     Rect childFinal = new Rect(0, arrangedHeight, width, childHeight);
                     ArrangeChild(child, childFinal, finalSize, orientation);
                     arrangedWidth = Math.Max(arrangedWidth, childWidth);
-                    arrangedHeight += childHeight + (child.IsVisible ? gap : 0);
+                    arrangedHeight += childHeight + (child.IsVisible ? spacing : 0);
                 }
                 else
                 {
                     double height = Math.Max(childHeight, arrangedHeight);
                     Rect childFinal = new Rect(arrangedWidth, 0, childWidth, height);
                     ArrangeChild(child, childFinal, finalSize, orientation);
-                    arrangedWidth += childWidth + (child.IsVisible ? gap : 0);
+                    arrangedWidth += childWidth + (child.IsVisible ? spacing : 0);
                     arrangedHeight = Math.Max(arrangedHeight, childHeight);
                 }
             }
 
             if (orientation == Orientation.Vertical)
             {
-                arrangedHeight = Math.Max(arrangedHeight - (hasVisibleChild ? gap : 0), finalSize.Height);
+                arrangedHeight = Math.Max(arrangedHeight - (hasVisibleChild ? spacing : 0), finalSize.Height);
             }
             else
             {
-                arrangedWidth = Math.Max(arrangedWidth - (hasVisibleChild ? gap : 0), finalSize.Width);
+                arrangedWidth = Math.Max(arrangedWidth - (hasVisibleChild ? spacing : 0), finalSize.Width);
             }
 
             return new Size(arrangedWidth, arrangedHeight);
@@ -250,4 +250,4 @@ internal virtual void ArrangeChild(
             child.Arrange(rect);
         }
     }
-}
\ No newline at end of file
+}
diff --git a/src/Avalonia.Controls/VirtualizingStackPanel.cs b/src/Avalonia.Controls/VirtualizingStackPanel.cs
index dee537029c1..5f7b63c57a6 100644
--- a/src/Avalonia.Controls/VirtualizingStackPanel.cs
+++ b/src/Avalonia.Controls/VirtualizingStackPanel.cs
@@ -200,7 +200,7 @@ internal override void ArrangeChild(
         private void UpdateAdd(IControl child)
         {
             var bounds = Bounds;
-            var gap = Gap;
+            var spacing = Spacing;
 
             child.Measure(_availableSpace);
             ++_averageCount;
@@ -208,13 +208,13 @@ private void UpdateAdd(IControl child)
             if (Orientation == Orientation.Vertical)
             {
                 var height = child.DesiredSize.Height;
-                _takenSpace += height + gap;
+                _takenSpace += height + spacing;
                 AddToAverageItemSize(height);
             }
             else
             {
                 var width = child.DesiredSize.Width;
-                _takenSpace += width + gap;
+                _takenSpace += width + spacing;
                 AddToAverageItemSize(width);
             }
         }
@@ -222,18 +222,18 @@ private void UpdateAdd(IControl child)
         private void UpdateRemove(IControl child)
         {
             var bounds = Bounds;
-            var gap = Gap;
+            var spacing = Spacing;
 
             if (Orientation == Orientation.Vertical)
             {
                 var height = child.DesiredSize.Height;
-                _takenSpace -= height + gap;
+                _takenSpace -= height + spacing;
                 RemoveFromAverageItemSize(height);
             }
             else
             {
                 var width = child.DesiredSize.Width;
-                _takenSpace -= width + gap;
+                _takenSpace -= width + spacing;
                 RemoveFromAverageItemSize(width);
             }
 
diff --git a/src/Avalonia.Diagnostics/DevTools.xaml b/src/Avalonia.Diagnostics/DevTools.xaml
index bb1b2e841e7..844670e7943 100644
--- a/src/Avalonia.Diagnostics/DevTools.xaml
+++ b/src/Avalonia.Diagnostics/DevTools.xaml
@@ -7,7 +7,7 @@
 
     <ContentControl Content="{Binding Content}" Grid.Row="1"/> 
     
-    <StackPanel Gap="4" Orientation="Horizontal" Grid.Row="2">
+    <StackPanel Spacing="4" Orientation="Horizontal" Grid.Row="2">
       <TextBlock>Hold Ctrl+Shift over a control to inspect.</TextBlock>
       <Separator Width="8"/>
       <TextBlock>Focused:</TextBlock>
@@ -17,4 +17,4 @@
       <TextBlock Text="{Binding PointerOverElement}"/>
     </StackPanel>
   </Grid>
-</UserControl>
\ No newline at end of file
+</UserControl>
diff --git a/src/Avalonia.Diagnostics/Views/TreePageView.xaml b/src/Avalonia.Diagnostics/Views/TreePageView.xaml
index a715ca6fc55..57398851ad9 100644
--- a/src/Avalonia.Diagnostics/Views/TreePageView.xaml
+++ b/src/Avalonia.Diagnostics/Views/TreePageView.xaml
@@ -5,7 +5,7 @@
       <TreeView.DataTemplates>
         <TreeDataTemplate DataType="vm:TreeNode"
                           ItemsSource="{Binding Children}">
-          <StackPanel Orientation="Horizontal" Gap="8">
+          <StackPanel Orientation="Horizontal" Spacing="8">
             <TextBlock Text="{Binding Type}"/>
             <TextBlock Text="{Binding Classes}"/>
           </StackPanel>
@@ -21,4 +21,4 @@
     <GridSplitter Width="4" Grid.Column="1"/>
     <ContentControl Content="{Binding Details}" Grid.Column="2"/>
   </Grid>
-</UserControl>
\ No newline at end of file
+</UserControl>
diff --git a/tests/Avalonia.Controls.UnitTests/StackPanelTests.cs b/tests/Avalonia.Controls.UnitTests/StackPanelTests.cs
index dca2c5df359..ba2716775ab 100644
--- a/tests/Avalonia.Controls.UnitTests/StackPanelTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/StackPanelTests.cs
@@ -54,11 +54,11 @@ public void Lays_Out_Children_Horizontally()
         }
 
         [Fact]
-        public void Lays_Out_Children_Vertically_With_Gap()
+        public void Lays_Out_Children_Vertically_With_Spacing()
         {
             var target = new StackPanel
             {
-                Gap = 10,
+                Spacing = 10,
                 Children =
                 {
                     new Border { Height = 20, Width = 120 },
@@ -77,11 +77,11 @@ public void Lays_Out_Children_Vertically_With_Gap()
         }
 
         [Fact]
-        public void Lays_Out_Children_Horizontally_With_Gap()
+        public void Lays_Out_Children_Horizontally_With_Spacing()
         {
             var target = new StackPanel
             {
-                Gap = 10,
+                Spacing = 10,
                 Orientation = Orientation.Horizontal,
                 Children =
                 {
@@ -150,11 +150,11 @@ public void Lays_Out_Children_Horizontally_Even_If_Larger_Than_Panel()
         [Theory]
         [InlineData(Orientation.Horizontal)]
         [InlineData(Orientation.Vertical)]
-        public void Gap_Not_Added_For_Invisible_Children(Orientation orientation)
+        public void Spacing_Not_Added_For_Invisible_Children(Orientation orientation)
         {
             var targetThreeChildrenOneInvisble = new StackPanel
             {
-                Gap = 40,
+                Spacing = 40,
                 Orientation = orientation,
                 Children =
                 {
@@ -165,7 +165,7 @@ public void Gap_Not_Added_For_Invisible_Children(Orientation orientation)
             };
             var targetTwoChildrenNoneInvisible = new StackPanel
             {
-                Gap = 40,
+                Spacing = 40,
                 Orientation = orientation,
                 Children =
                 {