script.aculo.us drag and sort scrolling bug

For those who uses the script.aculo.us drag and drop js libs, this is an explain for fixing a scrolling bug.
if your dragable element has a scrolling bar, when you try to scroll it also start dragging the element.
i fixed this bug, do the following steps and it will work perfectly:
open the file "dragdrop.js" for edit, after the following code:
if((tag_name = src.tagName.toUpperCase()) &&
( tag_name=='INPUT'
tag_name=='SELECT'
tag_name=='OPTION'
tag_name=='BUTTON'
tag_name=='TEXTAREA')) return;

add the following line:
if( src.undragable!=null) return;

this line means that if there's a tag in the element that called "undragable" so it wont move the element.

when you want to set an element with a scrollbar, just add the "undragable" tag to it and it will fix the problem, for example:

< d iv height="50%" width="100%"undragable style="height: 200px; overflow:auto;scrollbar-arrow-color: #808080; scrollbar-track-color: #FFFFFF; scrollbar-face-color: #FFFFFF; scrollbar-highlight-color: #808080; scrollbar-3dlight-color: #FFFFFF; scrollbar-darkshadow-color: #FFFFFF;scrollbar-shadow-color: #808080;"