Fixed Enhancement #442 - Add distinction for disabled keyframes on time track panel and or keyframe widget.

--> Gtk::STATE_INSENSITIVE + Gtk::ARROW_RIGHT for disabled keyframe.

<plus some comments>
Fix Bug #455 - Keyframe widget indicator remains white after drag and drop operation

change STATE_SELECTED to STATE_NORMAL in active keyframe when not dragging
Try to fix the bug but doesn't seem to work properly when combined with rotate.