[WPF] Reduced opacity of disabled buttons (#23)

Author: imalcolm1

src/Esri.Calcite.Wpf/Controls/Buttons.xaml

@@ -82,7 +82,7 @@
                             <Setter TargetName="bg" Property="Padding" Value="0" />
                         </Trigger>
                         <Trigger Property="IsEnabled" Value="False">
-                            <Setter TargetName="bg" Property="Opacity" Value="0.8" />
+                            <Setter TargetName="bg" Property="Opacity" Value="0.5" />
                         </Trigger>
                         <Trigger Property="IsEnabled" Value="True">
                             <Setter TargetName="bg" Property="Opacity" Value="1" />

src/TestApps/WpfTests/Samples/Buttons/Default.xaml

@@ -1 +1,4 @@
-<Button xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation">Test Passed</Button>
+<StackPanel xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation">
+    <Button xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" Margin="0,0,0,5">Default Enabled</Button>
+    <Button xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" IsEnabled="False">Default Disabled</Button>
+</StackPanel>