I am using nested dock objects. I find that if I close one tabbed window using the X icon, the control closes properly, leaving the other tabbed windows opened. However, if I try to close the tabbed window using the keyboard sequence Ctrl+F4, this also closes one of the tabs within another window! I have attached an example form. This contains a RadDock with 2 windows, DocumentWindow1 and DocumentWindow2. DocumentWindow1 also contains two document windows, DocumentWindow3 and DocumentWindow4. The sequence of events to reproduce this behaviour is as follows: - In designer mode: set focus on DocumentWindow2 and Save - Run app - Form opens with focus set on DocumentWindow2, as expected - Set focus on DocumentWindow1 - Set focus back to DocumentWindow2 - Press Ctrl+F4 to close DocumentWindow2 - This closes DocumentWindow2 but also closes DocumentWindow4 within DocumentWindow1. Please note that if I use the X button to close DocumentWindow2, only DocumentWindow2 gets closed, as expected.