Hi Clint David,
Sorry for the delay in getting back to you.
Query : Group Bar to be in a collapsed state when its actual Width reaches to 10.
We have achieved this using simple sample attached with this forum.
In the sample we have changed the width of GroupBar using Grid Splitter and we have defined the converter to bind the Width property to IsCollapsed property of GroupBar to achieve your requirement.
Please let us know if you have any other queries.
Regards,
P. Dinesh Kumar
GroupBarIsCollapsed_Forum_8ee81a9a.zip