GtkRange: Make drag gesture less agressive
GtkRange: Make drag gesture less agressive

Moving the mouse while pressing one of the steppers was making
the slider jump to the end, unexpectedly. This was caused by the
drag gesture kicking in when it shouldn't. Fix this by making
all drag gesture signal handlers only do something if we are in
a drag thats started on the slider.

https://bugzilla.gnome.org/show_bug.cgi?id=751050

jadahl/gtk,Adamovskiy/gtk,chergert/gtk,davidgumberg/gtk,alexlarsson/gtk,jadahl/gtk,grubersjoe/adwaita,Adamovskiy/gtk,jadahl/gtk,jadahl/gtk,Adamovskiy/gtk,chergert/gtk,davidgumberg/gtk,grubersjoe/adwaita,jigpu/gtk,alexlarsson/gtk,alexlarsson/gtk,alexlarsson/gtk,davidgumberg/gtk,jigpu/gtk,jigpu/gtk,chergert/gtk,davidgumberg/gtk,jigpu/gtk,grubersjoe/adwaita,jigpu/gtk,alexlarsson/gtk,grubersjoe/adwaita,grubersjoe/adwaita,chergert/gtk,Adamovskiy/gtk,jadahl/gtk,davidgumberg/gtk,alexlarsson/gtk,jadahl/gtk,davidgumberg/gtk,chergert/gtk,chergert/gtk,alexlarsson/gtk,chergert/gtk,Adamovskiy/gtk,jigpu/gtk,jigpu/gtk,Adamovskiy/gtk,grubersjoe/adwaita,jadahl/gtk,Adamovskiy/gtk,davidgumberg/gtk,davidgumberg/gtk,jadahl/gtk,grubersjoe/adwaita,jigpu/gtk,Adamovskiy/gtk,grubersjoe/adwaita,alexlarsson/gtk,chergert/gtk