Enable setting the origin point of the fill level
Submitted by Stefan Sauer (gstreamer, gtkdoc dev)
Some themes like clearlooks, clearlooks classic, darkilouche, ... draw a colored bar inside the GtkRange from the left to the slider position. I have a panorama position slider in my music application. The underlying GtkAdjustment goes from -1.0 to 1.0 (left to right). There this color bar looks really odd. Unfortunately the GtkAdjustment has no default/middle value.
If the theme wants to draw this, what about this: min,max are positive, start from left min,max are negative, start from right min,max have different signs, start from 0.0
invert everything for RTL languagages, and do simmilar for vertical ranges.