CMDIFrameWndEx::CanCovertControlBarToMDIChild
Visual Studio 2012
Called by the framework to determine whether the frame window can convert docking panes to tabbed documents
virtual BOOL CanCovertControlBarToMDIChild();
Override this method in a derived class and return TRUE to enable the conversion of docking panes to tabbed documents. Alternatively, you can set CMDIFrameWndEx::m_bCanCovertControlBarToMDIChild to TRUE.