Replying to myself:I found the solution to the font msg here.And the pixbuf error msg was solved by:sudo aptitude install gtk2-engines-pixbuf But still gksu or gksudo aptitude (and others like synaptic and others as well, i'd suspect ...) do not work.
I searched for:Unable to locate theme engine in module_pathand came up with some interesting results ...one idea that stick out means reinstalling the theme you are using:sudo apt-get install --reinstall gtk2-engines
sudo apt-get install gtk2-engines-pixbuf
sudo apt-get install --reinstall gtk2-engines gtk-murrine-engine gtk-equinox-engineor what ever ...
I'm currently trying to write a gnome shell extension. I would like to get the screenshot of a web page as a png file. To serve this purpose, I try to get the Gdk.Pixbuf to call savev... (widget is a WebKit.WebView):