clean up DemoMain fix distcheck svn path=/trunk/gtk-sharp/; revision=32961
and part of the stock browser svn path=/trunk/gtk-sharp/; revision=32053
fix some bugs in DemoEditableCells use more consistent tabs and spaces add a TODO of what is left use the using () pattern to dispose Dialogs automatically use args.RetVal when handling the DeleteEvent svn path=/trunk/gtk-sharp/; revision=32017