TAB exception

I have a dhtmlxGrid, on my webpage. I have set cells to be editable/ineditable based on certain conditions. The grid is mainly used to enable the user enter data on the webpage.
However, a js exception occurs when tabs are pressed consecutively. I have not been able to find out the exact sequence of events that lead to such an exception. It seems to happen erratically.
My debugger shows error in the following line, in the file dhtmlxgridcell.js

if (_isIE)this.obj.focus();this.obj.focus()

The dubugger hangs up at the second this.obj.focus() , stating

htmlfile: unexpected call to method property or access

The exception also sometimes occurs with mouse-clicks. The only peculiarity about this behaviour is that , it seems to occur only with “ed” type eXcells.

Please help.

Thanks.

Unfortunately we cannot reproduce this issue locally. Please provide any kind of sample or demo link where we can reproduce it.