Fix #13249 Mouse cursor on TextBox scrollbars shows as caret (#13542)

* Add styles to scrollviewers

* pr comment fix

* remove styles from scrollviewer

* add styles to scrollviewers

* add Ibeam to floating watermark

---------

Co-authored-by: Robert Mutniański <robert.mutnianski@inetum.com>

src/Avalonia.Themes.Fluent/Controls/ScrollViewer.xaml

@@ -44,10 +44,10 @@
           </ScrollContentPresenter>
           <ScrollBar Name="PART_HorizontalScrollBar"
                      Orientation="Horizontal"
-                     Grid.Row="1" />
+                     Grid.Row="1"/>
           <ScrollBar Name="PART_VerticalScrollBar"
                      Orientation="Vertical"
-                     Grid.Column="1" />
+                     Grid.Column="1"/>
           <Panel x:Name="PART_ScrollBarsSeparator"
                  Grid.Row="1"
                  Grid.Column="1"

src/Avalonia.Themes.Fluent/Controls/TextBox.xaml

@@ -131,7 +131,6 @@
                 <DockPanel x:Name="PART_InnerDockPanel"
                            Grid.Column="1"
                            Grid.ColumnSpan="1"
-                           Cursor="IBeam"
                            Margin="{TemplateBinding Padding}">
                   <TextBlock Name="PART_FloatingWatermark"
                              Foreground="{DynamicResource SystemAccentColor}"
@@ -171,6 +170,11 @@
                                     HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
                                     VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
                     </Panel>
+                    <ScrollViewer.Styles>
+                      <Style Selector="ScrollContentPresenter#PART_ContentPresenter">
+                        <Setter Property="Cursor" Value="IBeam" />
+                      </Style>
+                    </ScrollViewer.Styles>
                   </ScrollViewer>
                 </DockPanel>
                 <ContentPresenter Grid.Column="2" Grid.ColumnSpan="1" Content="{TemplateBinding InnerRightContent}"/>
@@ -228,6 +232,10 @@
       <Setter Property="BorderBrush" Value="{DynamicResource SystemControlErrorTextForegroundBrush}"/>
     </Style>
 
+    <Style Selector="^ /template/ TextBlock#PART_FloatingWatermark">
+      <Setter Property="Cursor" Value="IBeam"/>
+    </Style>
+    
     <Style Selector="^[UseFloatingWatermark=true]:not(:empty) /template/ TextBlock#PART_FloatingWatermark">
       <Setter Property="IsVisible" Value="True" />
     </Style>

src/Avalonia.Themes.Simple/Controls/ScrollViewer.xaml

@@ -31,7 +31,7 @@
                      Orientation="Vertical"/>
           <Panel Grid.Row="1"
                  Grid.Column="1"
-                 Background="{DynamicResource ThemeControlMidBrush}" />
+                 Background="{DynamicResource ThemeControlMidBrush}"/>
         </Grid>
       </ControlTemplate>
     </Setter>

src/Avalonia.Themes.Simple/Controls/TextBox.xaml

@@ -157,6 +157,11 @@
                                    TextAlignment="{TemplateBinding TextAlignment}"
                                    TextWrapping="{TemplateBinding TextWrapping}" />
                   </Panel>
+                  <ScrollViewer.Styles>
+                    <Style Selector="ScrollContentPresenter#PART_ContentPresenter">
+                      <Setter Property="Cursor" Value="IBeam" />
+                    </Style>
+                  </ScrollViewer.Styles>
                 </ScrollViewer>
                 <ContentPresenter Grid.Column="2"
                                   Grid.ColumnSpan="1"
@@ -183,6 +188,9 @@
     <Style Selector="^:disabled /template/ Border#border">
       <Setter Property="Opacity" Value="{DynamicResource ThemeDisabledOpacity}" />
     </Style>
+    <Style Selector="^ /template/ TextBlock#floatingWatermark">
+      <Setter Property="Cursor" Value="IBeam"/>
+    </Style>
 
     <Style Selector="^.clearButton[AcceptsReturn=False][IsReadOnly=False]:focus:not(TextBox:empty)">
       <Setter Property="InnerRightContent">