Using a CDialogImpl derived class as a dialog-based WTL/ATL app, I want to hide the main window when the user clicks the upper right "X" button (or presses Esc or Alt+F4).
Currently the "X" closes the dialog and ends the application.
I want to change this behaviour and only hide the dialog box instead of closing it. Is this possible?
I'm not sure if ATL/WTL provides some wrapper for this but in WinAPI, the function you are looking for is ShowWindow, which you would invoke as so:
ShowWindow(hwnd, SW_HIDE);
If you want this to happen when the application is closed, the message you need to handle is WM_CLOSE.
After a quick search, MSDN reveals CWindow::ShowWindow, which is the wrapper I mentioned earlier.