Hi Paul,
Thanks for bringing this to our attention. I do see this problem and have notified the Development team in this regard. We have logged a bug report Defect# 698 and will try our very best to address the same at the earliest. You could track the progress of this fix at the link shown below :
Defect #698 - MDIChild form toolbar visible after the child form is closed
We would like to inform you that the latest version v 3.3.0.0 will be released within 1 week. We appreciate your patience and cooperation.
Regards,
Ebenezer.P