In this case, we're finding several problems with the nested panes.

a. focus changes don't change pane state.

When you click on another window, and an active pane loses focus, the pane header still shows as the active pane.  Even if you click in client areas of other panes within the same pane manager, they don't update the pane active state (e.g. the orange caption bar).

b. show pane never does anything .  Each pane seems to be in its own docking pane container, and so it is the selected pane.  So calling ShowPane on it doesn't do anything except set focus to the contained window.

This is in 13.4.2.

Adrien

Check if OnIdleUpdateCmdUI of CXTPDockingPaneManager is called for second panemanager.

If not,  you need manually route it - m_paneManager.SendMessage(WM_IDLEUPDATECMDUI, 0, 0); 

where do I route this from?  Does that mean I need to subclass the pane manager for the parent pane or something? 

What messages get sent to panes when this idle processing is done?

So this is no use to me.  In my case, there are 3 layers deep of nesting.  

I have a pane manager with 3 panes and a client area.

in that client area is another pane manager with 2 tabs

on one of those tabs there is another pane manager with 3 panes

it's the inner-most one that is not updating.

Try catch WM_IDLEUPDATECMDUI in your Client window and pass it to PaneManager