Re: Event handler continues executing after its dialog is deleted

From:

"Tom Serface" <tom@camaswood.com>

Newsgroups:

microsoft.public.vc.mfc

Date:

Thu, 22 Oct 2009 10:30:39 -0700

Message-ID:

<FFF52830-8B9C-40D1-9E6D-1CF0E7563494@microsoft.com>

I have similar things happen with worker threads. So, I typically set some
sort of busy flag (in the object class) that I can set to check in my close
routine and if the thread is busy I alert it to close down, wait, and then
close when it's finished. Typically, this happens so quickly that the user
never even notices anything is going on, but it's easy enough to display a
message if the operation is going to take some time.

Tom

"Elizabeta" <Elizabeta@discussions.microsoft.com> wrote in message
news:026FDAFD-DF1B-4211-A8AC-E2F20F410A14@microsoft.com...

Hello
Consider the following code :

MyDlg::PostNcDestroy()
{
CDialog::PostNcDestroy();
delete this;
}

MyDlg::OnClose()
{
DestroyWindow();
}

MyDlg::OnMyBtnClick()
{
GetGeometricObject();<-- enter event loop here
this->m_combobox.EnableWindow(false); (*)

}

In the event handler OnMyBtnClick I am calling third party library
function
that starts event loop inside its implementation i.e uses PeekMessage or
GetMessage and DispatchMessage. i.e basically I have local event loop in
my
OnMyBtnClick. This third party function is for selecting circles,lines and
other geometric objects.

If the user closes my dialog while the event loop is running with (x Close
from the system menu) the dialog object is deleted. Then if the user
selects
some circle or something the event loop is terminated too. After the event
loop is terminated, execution continues in OnMyBtnClick function although
the
dialog is deleted, and crash occurs in ( *) where access to member data is
made.

How to prevent this situation ?
Is this common situation ?