make sure non editable combo closes on clicking top item. fixes #460

Author: ButchersBoy

MaterialDesignThemes.Wpf/ComboBoxAssist.cs

@@ -9,8 +9,6 @@ namespace MaterialDesignThemes.Wpf
 {
     public static class ComboBoxAssist
     {
-        #region ShowSelectedItem
-
         /// <summary>
         /// By default the selected item his hidden from the drop down list, as per Material Design specifications. 
         /// To revert to a more classic Windows desktop behaviour, and show the currently selected item again in the drop
@@ -32,7 +30,5 @@ public static void SetShowSelectedItem(DependencyObject element, object value)
         {
             element.SetValue(ShowSelectedItemProperty, value);
         }
-
-        #endregion
     }
 }

MaterialDesignThemes.Wpf/Themes/MaterialDesignTheme.ComboBox.xaml

@@ -487,7 +487,7 @@
                     <Condition Property="IsDropDownOpen" Value="True"/>
                 </MultiTrigger.Conditions>
                 <Setter TargetName="Underline" Property="Visibility" Value="Hidden"/>
-                <Setter TargetName="toggleButton" Property="Visibility" Value="Hidden"/>
+                <Setter TargetName="toggleButton" Property="BorderBrush" Value="Transparent"/>
             </MultiTrigger>
             <MultiTrigger>
                 <MultiTrigger.Conditions>