Use dconf functions from libmate-desktop
Use common GSettings function from libmate-desktop
GTK3 fix
Use about dialog from libmate-desktop
Sync translations with transifex
Remove autogenerated files
Sync translations with transifex
gtk3: fix run application dialog
Sync translations with transifex
Use better dconf path for added applets
Use GDK_WINDOW_XID for gtk+2 and gtk+3

It was introduced in gdk2 already so clean up the code.