Reopen modal dialog in MFC

I need to open a dialog box instantiated from the same class twice. When I try this

CdelmeDlg dlg;
dlg.DoModal();
dlg.DoModal();

The second call opens the dialog only for a split second, then it is closed. My bet was there is a leftover message in the message queue, so I added this in between the calls

MSG msgCur;
while (::PeekMessage(&msgCur, NULL, NULL, NULL, PM_REMOVE))
    ;

This solves the problem, but it feels like a wrong kind of thing to do. Is there a way to process the leftover mes开发者_开发知识库sage properly?

Don't call EndDialog( IDOK );

To handle the ok or cancel buttons being pressed just inherit OnOk or OnCancel ... Otherwise EndDialog is going to be called twice and you'll get the problem you are getting!

I actually think that YeenFei has a good point here.

It's been a while since i've played with MFC (thank goodness), but from memory, a timer, may or may not be called from the UI thread depending on which one you use. If the timer is being raised on the main UI thread, then a modal dialog will likely halt the main thread until it is dismissed, after which it would be called by the next timer. If the timer is raised on a separate thread, then your dialog is not blocking the main UI thread as it is being shown on a separate thread.

It's does seem more conceivable as YeenFei has pointed out that you want to re-show your dialog each time the timer is raised, hiding it when the user clicks on the button to dismiss it. That way, if the time is raised again, all it does is re-show the dialog whether it is currently open or not.

There is a great post here (www.eggheadcafe.com) about Timers and concurrency that you may find interesting, and may make things clearer than what I managed to accomplish.

Why can't you code it like this:

CdelmeDlg dlg; 
dlg.DoModal(); 

CdelmeDlg dlg1; 
dlg1.DoModal(); 

If you want your application run in background without UI, why not juz temporary hide it? a simple function this->ShowWindow(SW_HIDE) will do the job for you.

i think you should revise your design decision as it seem illogical for an application to behave like what you wanted it to be.

I solved the problem by hiding the dialog instead of closing it and launching another thread that first sleeps and then unhides the dialog.

May be your code has line:

m_pMainWnd = &dlg;

If so, than application after first call of DoModal() will finished, all other call of DoModal() will return -1. From MSDN:

The Microsoft Foundation Class Library will automatically terminate your thread when the window referred to by m_pMainWnd is closed. If this thread is the primary thread for an application, the application will also be terminated.