Forntend.Maui: workaround for button width on Gtk

Implemented workaround for incorrect width of some buttons on
Gtk (which were stretched to window width) by introducing
3 columns to grids in ReceivePage and SendPage. Buttons are
placed in central column, while other grid children span all
3 columns.

src/GWallet.Frontend.XF/ReceivePage.xaml

@@ -6,37 +6,44 @@
  xmlns:zxcm="clr-namespace:ZXing.Common;assembly=zxing">
  <Grid x:Name="mainLayout"
  RowDefinitions="Auto,Auto,Auto,Auto,Auto,Auto,Auto"
+ ColumnDefinitions="*,Auto,*"
  Padding="10,10,10,10"
  VerticalOptions="Center"
+ HorizontalOptions="Center"
  >
  <Label x:Name="balanceLabel"
  Text="..."
  HorizontalOptions="Center"
  Grid.Row="0"
+ Grid.ColumnSpan="3"
  />
  <Image
  x:Name="currencyImage"
  IsVisible="false"
  Grid.Row="1"
+ Grid.ColumnSpan="3"
  />
  <Label x:Name="fiatBalanceLabel"
  Text="..."
  HorizontalOptions="Center"
  Grid.Row="2"
+ Grid.ColumnSpan="3"
  />
  <Button x:Name="paymentButton"
  Text="..."
  IsEnabled="false"
  HorizontalOptions="Center"
  Clicked="OnSendPaymentClicked"
  Grid.Row="3"
+ Grid.Column="1"
  />
  <Button x:Name="copyToClipboardButton"
  Text="Copy address to clipboard"
  IsEnabled="true"
  HorizontalOptions="Center"
  Clicked="OnCopyToClipboardClicked"
  Grid.Row="4"
+ Grid.Column="1"
  />
  <zx:ZXingBarcodeImageView
  x:Name="qrCode"
@@ -46,7 +53,8 @@
  WidthRequest="200"
  HeightRequest="200"
  Grid.Row="5"
- >
+ Grid.ColumnSpan="3"
+ >
  </zx:ZXingBarcodeImageView>
  <Button
  x:Name="viewTransactionHistoryButton"
@@ -55,6 +63,7 @@
  HorizontalOptions="Center"
  Clicked="OnViewTransactionHistoryClicked"
  Grid.Row="6"
- />
+ Grid.Column="1"
+ />
  </Grid>
 </ContentPage>

src/GWallet.Frontend.XF/SendPage.xaml

@@ -8,12 +8,14 @@
  HorizontalOptions="FillAndExpand"
  RowSpacing="0"
  RowDefinitions="Auto,Auto,*,Auto,*,Auto,*,Auto,Auto"
+ ColumnDefinitions="*,Auto,*"
  >
  <StackLayout x:Name="transactionLayout"
  Orientation="Horizontal"
  HorizontalOptions="FillAndExpand"
  IsVisible="false"
  Grid.Row="0"
+ Grid.ColumnSpan="3"
  >
  <Label x:Name="transactionLabel"
  Text="Transaction proposal:"
@@ -41,11 +43,13 @@
  TextChanged="OnTransactionEntryTextChanged"
  IsVisible="false"
  Grid.Row="1"
+ Grid.ColumnSpan="3"
  />
 
  <StackLayout Orientation="Horizontal"
  HorizontalOptions="FillAndExpand"
  Grid.Row="2"
+ Grid.ColumnSpan="3"
  >
  <Label Text="Destination address:"
  HorizontalOptions="Start"
@@ -73,12 +77,14 @@
  IsSpellCheckEnabled="false"
  IsTextPredictionEnabled="false"
  Grid.Row="3"
+ Grid.ColumnSpan="3"
  />
 
  <Grid ColumnDefinitions="Auto,*,Auto"
  HorizontalOptions="FillAndExpand"
  Padding="0,10,0,0"
  Grid.Row="4"
+ Grid.ColumnSpan="3"
  >
  <Label Text="Amount:"
  HorizontalOptions="Start"
@@ -114,6 +120,7 @@
  <Grid x:Name="amountToSendLayout"
  HorizontalOptions="FillAndExpand"
  Grid.Row="5"
+ Grid.ColumnSpan="3"
  >
  <Grid.ColumnDefinitions>
  <ColumnDefinition Width="Auto"/>
@@ -137,6 +144,7 @@
  <Grid
  RowDefinitions="*,Auto"
  Grid.Row="6"
+ Grid.ColumnSpan="3"
  >
  <Label
  x:Name="passwordLabel"
@@ -157,13 +165,15 @@
  HorizontalOptions="Center"
  Clicked="OnSendOrSignButtonClicked"
  Grid.Row="7"
+ Grid.Column="1"
  />
  <Button x:Name="cancelButton"
  Text="Cancel"
  IsEnabled="true"
  HorizontalOptions="Center"
  Clicked="OnCancelButtonClicked"
  Grid.Row="8"
+ Grid.Column="1"
  />
  </Grid>
 </ContentPage>