panning in scrolledWindow/viewport

[Kees Kling <ckling upcmail nl>]

Hi all,

I'm working on a project to display images. These images are loaded in a 
Gtk::DrawingArea. Most of the time these images are too big, so I want 
to pan these images with the mouse. I tried a viewport and a scrolled 
window to pack this drawingarea and do the panning in a 
motion_notify_event by changing the values of the gtk::adjustment 
object. It is working, but terrible slow. It must be possible to do this 
faster, because when I load these images in the "Gimp" I can do this 
type of panning in a rather smooth way.

So my questions are

Must I use a viewport or scrolledwindow object?

Is it correct to pan by changing the adjustment objects or is there a 
better ( faster ) way?

Thanks

Kees Kling