There is indeed a GTK control called GtkVolumeButton that does kind of that http://library.gnome.org/devel/gtk/2.12/GtkVolumeButton.html or rather http://library.gnome.org/devel/gtk/2.12/GtkScaleButton.html but it is only in GTK 2.12, which is above what Inkscape currently requires. One of the conditions for upgrading the requirements are the version that is available in older distros. I am afraid GTK 2.12 is pretty new and won't be available widely.

Well,

I know that Ubuntu 8.04 (Hardy Heron) has 2.12.9 and is soon to be released. Where are the other distros at?

Joshua L. Blocher verbalshadow