make the sample 2.4 friendly
make the sample 2.4 friendly

svn path=/trunk/gtk-sharp/; revision=46842

antoniusriha/gtk-sharp,Gankov/gtk-sharp,sillsdev/gtk-sharp,antoniusriha/gtk-sharp,openmedicus/gtk-sharp,akrisiun/gtk-sharp,antoniusriha/gtk-sharp,akrisiun/gtk-sharp,akrisiun/gtk-sharp,openmedicus/gtk-sharp,Gankov/gtk-sharp,openmedicus/gtk-sharp,openmedicus/gtk-sharp,orion75/gtk-sharp,sillsdev/gtk-sharp,antoniusriha/gtk-sharp,Gankov/gtk-sharp,Gankov/gtk-sharp,sillsdev/gtk-sharp,sillsdev/gtk-sharp,antoniusriha/gtk-sharp,Gankov/gtk-sharp,openmedicus/gtk-sharp,openmedicus/gtk-sharp,orion75/gtk-sharp,Gankov/gtk-sharp,orion75/gtk-sharp,akrisiun/gtk-sharp,sillsdev/gtk-sharp,openmedicus/gtk-sharp,akrisiun/gtk-sharp,orion75/gtk-sharp,orion75/gtk-sharp