reduce height in ribbon button

Hello actipro team,

I try to set max height for 

<ribbon:Ribbon Name="m_ribbon" IsApplicationButtonVisible="False" IsMinimized="True" IsApplicationMenuOpen="False"
IsCustomizeQuickAccessToolBarMenuItemVisible="False" MaxHeight="45" IsCollapsible="False">
<ribbon:Ribbon.ApplicationMenu>
<ribbon:ApplicationMenu Visibility="Collapsed" >
</ribbon:ApplicationMenu>
</ribbon:Ribbon.ApplicationMenu>
<ribbon:Ribbon.TabPanelItems>
<ribbon:ToggleMinimizationButton />
</ribbon:Ribbon.TabPanelItems>

<ribbon:Ribbon.Tabs>
<ribbon:Tab Label="Datein" TabIndex="1" MaxHeight="10">

<ribbon:Group Label="Zwischenablage" MaxHeight="35">

<ribbon:Button ImageSourceSmall="{Image:Copy16}" MaxHeight="25" />

</ribbon:Group>

</ribbon:Ribbon.Tabs>
</ribbon:Ribbon>

AND

m_ribbon.CollapseThresholdSize = new Size(15, 15);

<Style TargetType="{x:Type ribbon:GroupPresenter}">
<Setter Property="MaxHeight"
Value="35"/>
</Style>

But the content size of ribbon button still is 93pixel.

So, how can we reduce the height of Ribbon?

Thanks,

Regards,

Hai.