feat: add avalonia basic ComboBox style.

src/Shared/HandyControlDemo_Shared/ViewModel/Common/InputElementDemoViewModel.cs

@@ -108,12 +108,12 @@ public class InputElementDemoViewModel : ViewModelBase
         SelectedDataList = DataList.Where((t, i) => i % 2 == 0).ToList();
     }
 
-    private void Search(string key)
+    private static void Search(string key)
     {
         Growl.Info(key);
     }
 
-    private List<string> GetComboBoxDemoDataList()
+    private static List<string> GetComboBoxDemoDataList()
     {
         var converter = new StringRepeatConverter();
         var list = new List<string>();

src/Shared/HandyControl_Shared/Themes/Styles/Base/ComboBoxBaseStyle.xaml

@@ -517,7 +517,7 @@
                                 <Condition Property="IsSelected" Value="True" />
                             </MultiTrigger.Conditions>
                             <Setter Property="Background" TargetName="Bd" Value="{DynamicResource PrimaryBrush}" />
-                            <Setter Property="Foreground" Value="White" />
+                            <Setter Property="Foreground" Value="{DynamicResource TextIconBrush}" />
                         </MultiTrigger>
                     </ControlTemplate.Triggers>
                 </ControlTemplate>

src/Shared/HandyControl_Shared/Themes/Theme.xaml

@@ -5662,7 +5662,7 @@
 								<Condition Property="IsSelected" Value="True" />
 							</MultiTrigger.Conditions>
 							<Setter Property="Background" TargetName="Bd" Value="{DynamicResource PrimaryBrush}" />
-							<Setter Property="Foreground" Value="White" />
+							<Setter Property="Foreground" Value="{DynamicResource TextIconBrush}" />
 						</MultiTrigger>
 					</ControlTemplate.Triggers>
 				</ControlTemplate>