Hi Paul,
Sorry for the inconvenience caused.
1. The panel does not actually gets docked to fill. It just fills the client area of the groupBarItem to act as a container. If it is docked to fill, you could not drag the panel out of the groupBar to the form.
2. This issue is because of the bug # 798 in GroupBar package, which has been fixed in latest release v.4.1 Beta.
GroupBarItem.Client cannot be set in the GroupBar''s collection editor.
If you would like to upgrade to v.4.1 Beta, please create a Direct-Trac incident in this regard, mentioning the forum post in the subject line. We will let you know the details of this release.
Please let me know if you have any questions. Thanks for using Syncfusion products.
Regards,
Mano