Merge pull request #4041 from AvaloniaUI/fixes/autocomplete-box-max-height

use fluent resource for max height of autocomplete box popup.

src/Avalonia.Themes.Fluent/Accents/BaseDark.xaml

@@ -160,6 +160,7 @@
     <x:Double x:Key="AppBarThemeMinimalHeight">24</x:Double>
     <x:Double x:Key="AppBarThemeCompactHeight">40</x:Double>
     <x:Double x:Key="AppBarExpandButtonCircleDiameter">3</x:Double>
+    <x:Double x:Key="AutoCompleteListMaxHeight">374</x:Double>
     <x:Double x:Key="AutoCompleteListBorderOpacity">0</x:Double>
     <Thickness x:Key="CheckBoxBorderThemeThickness">2</Thickness>
     <Thickness x:Key="CheckBoxCheckedStrokeThickness">0</Thickness>

src/Avalonia.Themes.Fluent/Accents/BaseLight.xaml

@@ -159,6 +159,7 @@
     <x:Double x:Key="AppBarThemeMinimalHeight">24</x:Double>
     <x:Double x:Key="AppBarThemeCompactHeight">40</x:Double>
     <x:Double x:Key="AppBarExpandButtonCircleDiameter">3</x:Double>
+    <x:Double x:Key="AutoCompleteListMaxHeight">374</x:Double>
     <x:Double x:Key="AutoCompleteListBorderOpacity">0</x:Double>
     <Thickness x:Key="CheckBoxBorderThemeThickness">2</Thickness>
     <Thickness x:Key="CheckBoxCheckedStrokeThickness">0</Thickness>

src/Avalonia.Themes.Fluent/AutoCompleteBox.xaml

@@ -26,6 +26,7 @@
     <Setter Property="FontFamily" Value="{DynamicResource ContentControlThemeFontFamily}" />
     <Setter Property="FontSize" Value="{DynamicResource ControlContentThemeFontSize}" />
     <Setter Property="Padding" Value="{DynamicResource TextControlThemePadding}" />
+    <Setter Property="MaxDropDownHeight" Value="{DynamicResource AutoCompleteListMaxHeight}" />
     <Setter Property="Template">
       <ControlTemplate>
         <Grid Name="PART_LayoutRoot">