Hide main MFC window while modal dialog is active?

4
votes

I have a native C++ MFC app. It has a main window based on CWnd, and user action can create a modal dialog. While the dialog is active, I want the main window to disappear, the dialog to be visible, and the main window's icon to remain in the task bar.

How can I accomplish this?

If I hide the main window (ShowWindow(SW_HIDE)), the task bar icon disappears. If I minimize the main window (SW_MINIMIZE), the icon remains. However, since the dialog is owned by the main window, this also hides the dialog.

After the dialog is created, clicking on the task bar icon makes the dialog visible. Naturally, I do not want to require the user to do this.

Even if I insert ShowWindow(SW_SHOW) in the dialog's OnInit handler, the dialog remains not visible. Spy++ shows that its visible bit is set, though. Same is true if I add SetWindowActive to OnInit.

I am not interested in changing the UI design. While the dialog is active, the user interacts only with it, and is not interested in anything in the main window. Therefore, the main window should disappear.

Using Windows VS2005 under WinXP32.

4
c++mfcmodal-dialog

4 Answers

1
votes

Well, in the block of code where you create the dialog and show it modal, you can do whatever you want to the main window of your app (show/hide) as long as you make the desktop window the parent of your dialog. Usually, the constructor for CDialog and derivatives takes a default argument of NULL for the parent window in which the framework ends up substituting AfxGetMainWnd(). Instead pass CWnd::GetDesktopWindow() as the parent of your dialog and then you should probably be able to hide your main window. However, you still might have a problem with the taskbar--but I'll let someone else give hints since I know nothing offhand about it.

1
votes

In OnInitDialog, add following codes

//Set windows size zero, the windows disappear.
MoveWindow(0,0,0,0);

//If you want it invisible on taskbar. add following codes.
DWORD dwStyle = GetWindowLong(GetSafeHwnd(), GWL_EXSTYLE);
dwStyle &=~WS_EX_APPWINDOW;   
dwStyle |= WS_EX_TOOLWINDOW;     
SetWindowLong(GetSafeHwnd(), GWL_EXSTYLE, dwStyle);
0
votes

You're fighting the OS. A modal dialog, by definition, disables but does not hide the "main" (parent) window. If you wanted another window, make a second one, but don't tell the OS to treat it as a modal dialog over the first window.

0
votes

Perhaps you can resize the main window to a really small size and always keep it behind the modal dialog.