How can I implement split windows?

I want to split my main window vertically so there's a sizing bar in the middle but I'm not sure how to go about it. I imagine I could create two windows with a gap between them then handle mouse events to do sizing manually but I thought I'd post here to see if there's a simpler method.

Thank you

Simpler would be using MFC with its class CSplitterWnd. Or, at least look at its source code...

If you understand MFC, use Victor's suggestion. Otherwise think of your window as a parent, then create two child windows in it. Handle the WM_MOUSEMOVE in the parent. The two child windows operate independantly. Don't forget to handle the WM_SIZE.

-Erik