To remove the default MouseOver
behaviour on the Button
you will need to modify the ControlTemplate
. Changing your Style
definition to the following should do the trick:
<Style TargetType="{x:Type Button}">
<Setter Property="Background" Value="Green"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type Button}">
<Border Background="{TemplateBinding Background}" BorderBrush="Black" BorderThickness="1">
<ContentPresenter HorizontalAlignment="Center" VerticalAlignment="Center"/>
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
<Style.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="Background" Value="Red"/>
</Trigger>
</Style.Triggers>
</Style>
EDIT: It's a few years late, but you are actually able to set the border brush inside of the border that is in there. Idk if that was pointed out but it doesn't seem like it was...