Horizontal scrollbar disappear on collapsed datagrid [BUG]

[aswzen]

I found a bug on datagrid and happened on latest Chrome and Firefox

Case :
I have a datagrid with collapsed:true and 5 columns that configured with fixed width..
when i open/expand the datagrid, it will hide the remain column that overwidth on the right side, it's ok. but i can't scroll it to the right because the scrollbar is disappear. just like the image below



here the fiddle
http://jsfiddle.net/aswzen/bgy4kg2k/6/

why this is happened?

[jarry]

Please download the patch from http://www.jeasyui.com/download/downloads/jquery-easyui-1.4.2-patch.zip

[aswzen]

thank you ..
your patch works perfectly