The set_color signal is a signal that is emitted on an SPDesktop object by various color-selecting widgets and commands and is processed by the various selections and color-displaying widgets.
The signal carries at least one parameter which specifies whether this color is to be applied to the stroke or to the fill. Some callbacks use it, some ignore it (see below).
Ideally, the signal may also carry a more complex ColorChange struct as a parameter, which would indicate which channels in which color spaces are to be changed by what values. This will allow us to set e.g. transparency of the fill of selected objects without changing the fill color, or vary the HSV saturation of the current stroke color without changing the hue. (See [http://sourceforge.net/tracker/index.php?func=detail