Background is changing in Mouse_Leave but not in Mouse_Enter

Question

I am just getting into WPF. I have two event handlers:

private void Mouse_Enter(object sender, MouseEventArgs e)
{
    ((Button)sender).Background = Brushes.Red;
}
private void Mouse_Leave(object sender, MouseEventArgs e)
{
    ((Button)sender).Background = Brushes.Black;
}

When the mouse enters the button's area, nothing happens. However, when leaving the button's area, the button does go black. I have put a breakpoint inside Mouse_Enter and it is definitely executing the method, just doesn't change the background color.

How to fix it? Thanks!

Does your button change color to the default "button hover" color when your mouse enters? — Fleury26, Nov 23 '17 at 20:55
If it doesn't need to be in the c# code and can be in the XAML i suggest looking at [this answer](https://stackoverflow.com/questions/20073294/change-color-of-button-when-mouse-is-over) — Fleury26, Nov 23 '17 at 21:27
There is a lot more to re-styling a button than just overriding the background color. The default template can be found [here on msdn](https://learn.microsoft.com/en-us/dotnet/framework/wpf/controls/button-styles-and-templates) — Manfred Radlwimmer, Nov 24 '17 at 08:24

Dark Templar · Answer 1 · 2017-11-24T11:06:45.427

This is happening because there is a "built-in" trigger in the default button template that's causing the button to ignore your attempts to change it's background on a MouseEnter event, you will need to edit the template and disable the trigger first, follow these steps:

In the Visual Studio editor right click on your button and pick "Edit Template" then "Edit a Copy..." name your style whatever you want and look through the XAML for a trigger called "IsMouseOver" and delete the 2 lines below.

                    <ControlTemplate.Triggers>
                        <Trigger Property="IsDefaulted" Value="true">
                            <Setter Property="BorderBrush" TargetName="border" Value="{DynamicResource {x:Static SystemColors.HighlightBrushKey}}"/>
                        </Trigger>
                        <Trigger Property="IsMouseOver" Value="true">
    --- Delete this line    <Setter Property="Background" TargetName="border" Value="{StaticResource Button.MouseOver.Background}"/>
    --- Delete this line    <Setter Property="BorderBrush" TargetName="border" Value="{StaticResource Button.MouseOver.Border}"/>
                        </Trigger>
                        <Trigger Property="IsPressed" Value="true">

Thanks a lot, but I really want to do it using code-behind. Not for production purposes of course, but just for learning. Could you please explain how would I fix it without using XAML triggers? Thanks again! — Gabriel Haddad, Nov 24 '17 at 10:05

Background is changing in Mouse_Leave but not in Mouse_Enter

1 Answers1