diabled button state for default PopupBox button style

Author: ButchersBoy

MainDemo.Wpf/MainWindow.xaml

@@ -195,8 +195,8 @@
                         <materialDesign:PopupBox DockPanel.Dock="Right" PlacementMode="BottomAndAlignRightEdges" StaysOpen="False">
                             <StackPanel>
                                 <Button Content="Hello World" Click="MenuPopupButton_OnClick"/>
-                                <Separator/>
                                 <Button Content="Nice Popup" Click="MenuPopupButton_OnClick"/>
+                                <Button Content="Can't Touch This" IsEnabled="False" />
                                 <Separator/>
                                 <Button Content="Goodbye" Click="MenuPopupButton_OnClick"/>                                
                             </StackPanel>

MaterialDesignThemes.Wpf/Themes/MaterialDesignTheme.PopupBox.xaml

@@ -93,7 +93,12 @@
                                                                                          To="0.1" Duration="0"/>
                                                                     </Storyboard>
                                                                 </VisualState>
-                                                                <VisualState Name="Disabled"/>
+                                                                <VisualState Name="Disabled">
+                                                                    <Storyboard>
+                                                                        <DoubleAnimation Storyboard.TargetProperty="Opacity"
+                                                                                         To="0.48" Duration="0"/>
+                                                                    </Storyboard>
+                                                                </VisualState>
                                                             </VisualStateGroup>
                                                         </VisualStateManager.VisualStateGroups>
                                                         <Border x:Name="MouseOverBorder"