Q:

Remove the button border including the 'tab event' in wpf?

I manage to remove the button border completely by using this style
    <Style x:Key="TransparentStyle" TargetType="{x:Type Button}">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="Button">
                    <Border Background="Transparent">
                        <ContentPresenter/>
                    </Border>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

However, how to remove the dotted black border that appears with the TAB key?

A:

that would be the FocusVisualStyle showing that dotted line, try to set it to x:Null

