PR# 12965 Restoring default preferences does not always work

Restoring the default preferences in the Preferences window does not always work.
This should be added to the Critical Bugs list.

Delete ~/.es directory.
Compile sample graphical application.
Select Tools/Preferences.
Expand the Compiler node (in tree view).
Change Maximum Processors to 3.
Click on Restore Defaults button and confirm.
Maximum number of processors preferences should have been reset to 0 but is
   still shown as 3.  Note that this is not just a display issue - if I exit
   estudio at this point and restart and examine this preference, it has the
   value 3.
However, do not exit estudio.
Switch to Flat view, then back to Tree view.  Now the maximum number of 
   processors value is 0.