Comment 3 for bug 573090

I can confirm this. However I don't really know what's the expected behaviour.

Current behaviour:
Scrolling on the indicator icon modifies the volume.
Clicking on the indicator icon and scrolling on the icon does not modify the volume.
Clicking on the indicator icon and moving the mouse to the sound scroll bar modifies the volume.

I agree that it would be nice to be able to modify the volume when the mouse is over the icon, even when the indicator was clicked and is showing the options.

A developer opinion would be useful here.