Can I get details on what the change is? What file(s) and what code would be great.

I have been experiencing an occasional crash in V22 when ClosePane is called because our client window is being destroyed unexpectedly. The only guess I have is that somehow the docking pane manager's m_pLayout is null which is preventing the client window from being parented to the manager when the pane is closed. I do know that when the mini window is destroyed, our client window gets destroyed by the OS as it is still a child. 

I have yet to detect how it doesn't get re-parented though as when I debug the code the re-parenting of the client window from the container to the manager always succeeds. This is quite random but our crash data analysis from customer boxes points to issues with our client window that I have posited is due to the window being destroyed and the memory deleted. Or somehow the memory for the window object has been overwritten. Now I see that release note and am keen on back porting any fix in V24 to V22.