The multi-number button/value dragging feature needs some kind of visual indication to show users that they can drag vertically to affect more than just the current value.
The visual hint should show while click and hold and while dragging vertically. The hint should disappear once mouse moves horizontally beyond multi-number threshold.
Design and Development
I will create the mockup for visual appearance, followed by implementation by @Campbell Barton (campbellbarton)
Release notes:
http://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.70/UI#Multi-Number_Button_Editing