Free MFC Source Code

CSizingControlBar: resizable control bars by Cristi Posea.
Do you need an edit control, tabbed tree or other window to be docked to the frame's sides? But after browsing through the MFC documentation, didn't find nothing like this? You came to the right place. CSizingControlBar is an easy to use collection of classes, allowing you to focus on your application needs rather than on implementation tweaks.
Quick links: download, documentation, faq, change log

Dynamic child window positioning by Hans Bühler.
A nice layout manager (code which resize controls automatically). As a sample, there is a class derived from CSizingControlBar which holds a dialog, so here are the docking dialogs you asked for :)

Docking a window inside an ActiveX control by Greg Winker.
This excellent article explains not only how to implement an ActiveX control which can have docking windows, but also shows how to place a ActiveX controls on the docking window itself.

Views on CSizingControlBar by Rob Finch.
How to host views on the control bars using a dummy parent frame.

Docking Views (2) by M.Shams Mukhtar.
Another way to host views on your resizable control bars.

How to verify the bar state info by Cristi Posea.
LoadBarState() gives you headaches? This article provides a function you can call to verify the state info before calling LoadBarState().

How to dock bars side by side by Cristi Posea.
Explains how to dock a bar next to a previously docked one. This article takes a closer look at the problem, and comes with a more general solution.