Headers / Grid not same size

Hello,

I have a strange problem, but maybe it have a quick fix.

While using IE8 in Compatibility Browser Mode, headers will differ in size from actual columns.
This is not happening in IE8 Browser mode.

Is that a known issue?
Can this be solved?
What other information should I provide

(I use dhtmlxGrid v.2.6 Professional edition build 100722 )

Unfortunately the issue cannot be reproduced locally.
The following example works well in ie8 compatibility mode:
dhtmlx.com/docs/products/dht … _grid.html