Custom dropdown for CComboBox

I'm trying to create a custom dropdown for a derivative of CComboBox. The dropdown will be a calendar control plus some 'hotspots', e.g.

So I figure the best way to achieve this is to have a simple CWnd-derived class which acts as the parent to the calendar control, and have it paint the hotspots itself.

The window needs to be a popup window - I think - rather than a child window so that it isn't clipped. But do开发者_如何学Cing this causes the dialog (on which the combobox control is placed) to stop being the topmost (foreground?) window, leading to its frame being drawn differently:

alt text http://img693.imageshack.us/img693/3474/35148785.png

This spoils the illusion that the dropdown is part of the combobox since its acting more like a modal dialog at this point. Any suggestions on how I make the custom dropdown behave like the regular dropdown?

Are there any other pitfalls I need to watch out for, e.g. focus and mouse capture issues?

When you create your popup window, you need to specify its owner. Owned popup windows will activate their owner when you activate them. Not specifying an owner will cause your window to get activated, which causes the change in the owner you're seeing.

Yeah I had this problem once. A quick google makes me suspect I solved this by using CreateWindowEx() and specifying WS_EX_NOACTIVATE. I have some other code that achieves the same effect by making the window with WS_EX_TOOLWINDOW rather than as a popup window, but I'm not sure of why that was done that way, my intuition would say that making it a popup window would be the way to go.

You can find in the following links two sample project that put in the CComboBox dropdown window a CTreeCtrl or a CListCtrl controls ... similar, you can put whatever you need there. Here is the links:

Tree ComboBox Control

and

List ComboBox Control

I hope this help you.