MultiImageView_6.xaml

    <RepeatButton.Style>
        <Style TargetType="{x:Type RepeatButton}">
            <Style.Triggers>
                <DataTrigger Binding="{Binding RelativeSource={RelativeSource Mode=Self}, Path=IsEnabled}" Value="True">
                    <Setter Property="Content">
                        <Setter.Value>
                            <Path Data="M 9 0 L 9 10 L 0 5 Z"
                                  Fill="{x:Static SystemColors.ControlTextBrush}"
                                  Stroke="{x:Static SystemColors.ControlTextBrush}" />
                        </Setter.Value>
                    </Setter>
                </DataTrigger>
                <DataTrigger Binding="{Binding RelativeSource={RelativeSource Mode=Self}, Path=IsEnabled}" Value="False">
                    <Setter Property="Content">
                        <Setter.Value>
                            <Path Data="M 9 0 L 9 10 L 0 5 Z"
                                  Fill="{x:Static SystemColors.ControlDarkDarkBrush}"
                                  Stroke="{x:Static SystemColors.ControlDarkDarkBrush}" />
                        </Setter.Value>
                    </Setter>
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </RepeatButton.Style>
</RepeatButton>