I have been created a tab control in dialog box (we called as Dialog Main). I add 3 frameless dialog box (we called as dialog A, Dialog B, Dialog C) in the tab control. The tab control working fine. I add three button (OK button, Cancel button ,Apply Button) in each frameless dialog box. However, when I clicked Cancel button in dialog A only dialog was closed. I want all dialogs(Dialog Main, dialog A, Dialog B, Dialog C) to be closed when I clicked OK of Cancel button inside each frameless dialog box(dialog A, Dialog B, Dialog C). Please anybody help me???