One place that can fire off updating is the internal OnIdle. This is a fake message handler, called from the MFC message loop. So, you'll get updates a lot, but only when the message queue has "calmed down". So, if you get it a lot, it's because you don't have a lot else going on. Iain. I am one of "those foreigners coming over here and stealing our jobs". Yay me!

It 'isn't straightforward' in the same sense that casting a double to char would be. The types are not the compatible, not even the same size.

I'm getting the same behavior as I suspect you did trying to override the CreateCombo function in a property class derived from CMFCPropertyGridProperty. Did you ever resolve this? AlexJ

Look at this one as well: http://berenger.eu/blog/2011/10/06/c-openmp-a-shared-memory-quick-sort-with-openmp-tasks-example-source-code/[^] Visit my project: Derivative Calculator

Thanks for the responses. I managed to find a breakpoint for some function that releases memory. Need to brush up on my assembly perhaps? :-D Not quite what I asked, however a chap at work suggested typing $err into the watch window, this dispays the current value of GetLastError so I can step through code seeing where it changes.