Well according to this article. You must set the IsSharedSizeScope
property in a parent control to True
. So probably it should look more like:
<ItemsControl Grid.IsSharedSizeScope="True">
<Grid>
<Grid.RowDefinitions>
<RowDefinition SharedSizeGroup="CustomControlGroup" />
<RowDefinition SharedSizeGroup="CustomControlGroup" />
<Grid.RowDefinitions>
</Grid>
</ItemsControl>
Here is another example from the MSDN. IMHO, the first article is more understandable.