From Valeri Fine:

   - TQtClientWidget.cxx, TQtClientFilter.cxx:
     An extra protection against a dead pointer of the grabbing widget

   - TQtClientGuard.cxx:
     Remove a redundant "disconnect" to improve the performance.

   - TGQt.cxx:
     Add Olivier's comment about the "fill area pattern convention"

   - TQtWidget.cxx:
     An extra protection against dead pointers in the ROOT GUI

     Extra ROOT env parameter "Gui.Prompt yes/no" to enable/disable
     RootCint prompt for Qt based ROOT application.

     Add an instantiation of TQLock class (CMS user demand)

   - rootcinrule.pri rootlibs.pri
     Fix typo: $QTROOTSYS should be $QTROOTSYSDIR

   - TQtWidget.h, TQtThread.h, TQtClientWidget.h, TQtClientFilter.h, TGQt.h
     Add CPP flags to facilitate the coming QT4 transition.


git-svn-id: http://root.cern.ch/svn/root/trunk@12499 27541ba8-7e3a-0410-8455-c3a389f83636