[net7.0] Use same type converter for Brush as for Color to enable XAM…

…L completion (#16639)

* Use same type converter for Brush as for Color to enable XAML completion

* Add converter for VisualElement.Background

* Update src/Controls/src/Core.Design/AttributeTableBuilder.cs

Co-authored-by: Samantha Houts <samhouts@users.noreply.github.com>

---------

Co-authored-by: ET <48451158+etvorun@users.noreply.github.com>
Co-authored-by: Rui Marinho <me@ruimarinho.net>
Co-authored-by: Samantha Houts <samhouts@users.noreply.github.com>

src/Controls/src/Core.Design/AttributeTableBuilder.cs

@@ -33,6 +33,12 @@ public AttributeTableBuilder()
 			AddMemberAttributes("Microsoft.Maui.Controls.VisualElement", "FlowDirection",
 			   new TypeConverterAttribute(typeof(FlowDirectionDesignTypeConverter)));
 
+			// We need to supersede type converter declared on VisualElement.Background,
+			// otherwise VS will use generic "all strings allowed" converter which
+			// does not expose color values, i.e. no XAML intellisense popup
+			AddMemberAttributes("Microsoft.Maui.Controls.VisualElement", "Background",
+			   new TypeConverterAttribute(typeof(ColorDesignTypeConverter)));
+
 			AddMemberAttributes("Microsoft.Maui.Controls.ItemsView", "ItemsLayout",
 			   new TypeConverterAttribute(typeof(ItemsLayoutDesignTypeConverter)));
 
@@ -61,6 +67,7 @@ public AttributeTableBuilder()
 			//new System.Windows.Markup.MarkupExtensionReturnTypeAttribute (),
 			);
 
+			AddTypeAttributes("Microsoft.Maui.Controls.Brush", new TypeConverterAttribute(typeof(ColorDesignTypeConverter)));
 			AddTypeAttributes("Microsoft.Maui.Graphics.Color", new TypeConverterAttribute(typeof(ColorDesignTypeConverter)));
 			AddTypeAttributes("Microsoft.Maui.GridLength", new TypeConverterAttribute(typeof(GridLengthDesignTypeConverter)));