Question

I am trying to make a simple mouseover effect on a button, It does change the color when mouse is over but the color is immediately changed to the default button background… how can I override this behavior?

this is my code:

Style myBtnStyle = new Style();
Trigger bla = new Trigger() { Property = IsMouseOverProperty, Value = true };
bla.Setters.Add(new Setter(Control.BackgroundProperty, Brushes.Black));
myBtnStyle.Triggers.Add(bla);
button2.Style = myBtnStyle;

Answer 1

According to this post, that fancy animation is built into and to remove it, you’re going to need to override the ControlTemplate for your Button. Fortunately, that isn’t too hard. I used this post as source material and came up with the following Style that gives you the idea.

<Style x:Key="MouseOverButtonStyle" TargetType="Button">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="Button">
                <ControlTemplate.Resources>
                    <Style x:Key="ShadowStyle">
                        <Setter Property="Control.Foreground" Value="LightGray" />
                    </Style>
                </ControlTemplate.Resources>
                <Border Name="border" BorderThickness="1" Padding="4,2" BorderBrush="DarkGray" CornerRadius="3" Background="{TemplateBinding Background}">
                    <Grid >
                        <ContentPresenter HorizontalAlignment="Center" VerticalAlignment="Center" Name="contentShadow" Style="{StaticResource ShadowStyle}">
                            <ContentPresenter.RenderTransform>
                                <TranslateTransform X="1.0" Y="1.0" />
                            </ContentPresenter.RenderTransform>
                        </ContentPresenter>
                        <ContentPresenter HorizontalAlignment="Center" VerticalAlignment="Center" Name="content"/>
                    </Grid>
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
    <Style.Triggers>
        <Trigger Property="IsMouseOver" Value="True">
            <Setter Property="Background" Value="Beige" />
        </Trigger>
    </Style.Triggers>
</Style>

Update:
If you’re dead set on applying the Style in code and you don’t want to use a ResourceDictionary (probably the better way to do it), you can load the Style dynamically using XamlReader.Load:

            const string xaml = @"
<Style xmlns='http://schemas.microsoft.com/winfx/2006/xaml/presentation'
       xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml'
       TargetType='Button'>
    <Setter Property='Template'>
        <!--- Omitted For Clarity --->
    </Setter>
    <Style.Triggers>
        <Trigger Property='IsMouseOver' Value='True'>
            <Setter Property='Background' Value='Beige' />
        </Trigger>
    </Style.Triggers>
</Style>";
            var encoding = new ASCIIEncoding();
            var bytes = encoding.GetBytes(xaml);
            var style = (Style)XamlReader.Load(new MemoryStream(bytes));
            Button1.Style = style;