Drag and drop in MFC Dialog

Question

I'm trying to add drag and drop functionality to a control on a property page which is programmatically "wrapped" inside an MFC dialog at runtime. This "wrapping" involves instantiating the property page as a member of the dialog, and then resizing it and positioning it to the dimensions of a picture control which is on the dialog in the.rc file. I'm not sure why things were done this way, other than to maybe standardise the appearance of property pages in the app, but in any case I end up with this complicated hierarchy of windows, a control inside a property page inside a picture control inside a dialog.

The control which I want to accept dragged files has DragAcceptFiles invoked on it, but I think the WM_DROPFILES message for the control is being discarded before it reaches the control, because one of the parent windows doesn't accept dragged files. I considered calling DragAcceptFiles on all the parents, and passing WM_DROPFILES down the chain of windows, but I don't want to do that because they won't have handlers to accept the files, and will show the icon indicating files can be dropped on them regardless.

Any help on figuring out how to get the WM_DROPFILES message to my control would be much appreciated.

Answer 1

At the parent level, implement an override for virtual CDialog::PreTranslateMessage(MSG* pMsg)

This gives you a chance to see the WM_DROPFILES message and redirect them to a handler in the property page.

Answer 2

I figured this out in the end by calling CWnd::BringWindowToTop() on both the control I wanted to drag files onto, and also the dialog that the control was on.