WinGui: Block users from attempting to overwrite their input file. 

git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@6465 b64f7644-9d1e-0410-96f1-a4d463321fa5
WinGui: Improve exit while encoding error message.

git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@6466 b64f7644-9d1e-0410-96f1-a4d463321fa5
WinGui: Fix Queue Edit. Post action to update UI widgets wasn't firing.

git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@6467 b64f7644-9d1e-0410-96f1-a4d463321fa5
WinGui: Fix for quality slider on queue edit. Was not updating correctly.

git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@6468 b64f7644-9d1e-0410-96f1-a4d463321fa5