Show/Hide dialog bar and update menu

Hi

I have a dialog bar on which many dialog boxes reside. And there is a menu which shows/hides the dialog bar. Now i have a problem. i.e when the user drags the dialog bar from its docked position and kills it, i want the menu to be unchecked. Like any standard vc++ application view->toolbar and view->statusbar menu item. But i see that WM_CLOSE or WM_SHOWWINDOW messsages are not getting generated when user drags that window out and kills it. How can i fix this problem?
What exactly happens when user drags that window out and kills it??Any help is greately appreciated.

Thanks
Shashi

what is a dialog bar.You mean tool bar.
sorry for that.
Gupta.