I found a bug on datagrid and happened on latest
Chrome and FirefoxCase :
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?