I just installed the GroupBoxHelper widget from the appstore and it works great! Kudos to Marcel! I have one question - how can I style the GroupBox header to have a different color than the default/theme color. I tried what I thought would do this - duplicating the mx-groupbox-header class and changing the background color, then putting this class in the class property of the GroupBoxHelper widget - and it changed the background color of the body of the groupbox once expanded. this didn't have any effect on the header background color. Thanks in advance!