Double-click the scrollbar component in your movie's library, view its actions.
Find this function definition at line 191 in the AS:
Code:
FScrollBarClass.prototype.scrollIt = function (inc, mode)
Before the ending curly brace, insert the following:
Code:
_root.scrolling=true;
Now find this function definition at line 264:
Code:
FScrollBarClass.prototype.stopScrolling = function()
Before the ending curly brace, insert the following;
Code:
_root.scrolling=false;
You will now be able to reference your newly created _root.scrolling variable in your scripts.
There may be a more elegant way, but this works.