Strange behaviour in multi header grid

I'm facing a strange behaviour in multi-span header grid. On changing the column width, a portion in the end of the grid doesn't get painted.

This behaviour is not consistent. On constantly changing width at times it gets rectified, but appears again on a random basis.

I've the following function being called on width change event

grid.onColumnWidthChanged = function(){
this.getHeadersTemplate(1, "center").refresh();
};

Please suggest.

Can you post a sample and instructions how to reproduce this?