Fixes to the notebook code to better handle removing of pages.  Also, added a few mutexes where there should have been.
Fixes to the notebook code to better handle removing of pages.  Also,
added a few mutexes where there should have been.

OS2World/LIB-DynamicWindows,OS2World/LIB-DynamicWindows,OS2World/LIB-DynamicWindows