or
<Style TargetType="telerik:RadButton"> <Style.Triggers> <Trigger Property="IsMouseOver" Value="true"> <Setter Property="Background" Value="Red"/> </Trigger> </Style.Triggers> </Style><Window x:Class="BusyIndicatorTest.MainWindow" xmlns:Controls="clr-namespace:Telerik.Windows.Controls;assembly=Telerik.Windows.Controls" Title="MainWindow" Height="350" Width="525"> <Grid> <Controls:RadBusyIndicator IsBusy="True" IsIndeterminate="False" ProgressValue="50.0"> <ListBox> <ListBoxItem Content="Some Content 1"/> <ListBoxItem Content="Some Content 2"/> </ListBox> </Controls:RadBusyIndicator> </Grid> </Window>