I faced some problem that I can't solve.

Here is the thing. I have a buffered store and a grid.
In the store I specified the 'groupField' config option and specified appropriate feature in the grid.

When I run the application the grid separates data by groups. But! It doesn't show '+'/'-' buttons. Because of that I can't expand or collapse groups.

When I delete 'buffered:true' option in the store, expand/collapse buttons appear.

I found simmilar topic here: http://www.sencha.com/forum/showthread.php?237296-Scrolling-issues-in-grouping-grids-using-buffered-stores-(in-a-border-layout)&

In that topic described an issue with scrolling but there are no anything about expand/collapse functionality.
If you familiarize with example provided in that topic you'll probably see what I'm talking about.

You can find my code sample (pretty much the same sample as provided in the topic above) here: https://github.com/vdaiev/ExtJs-4.1.1-Grid-Grouping-with-Buffered-Store

hank you!