problem with display of frozen checkbox column

[mgraso]

I have two grids: master/details. They both display a column of check boxes. The first image shows the correct display, I render the column header myself with an image of a check mark. When I click on an item in the master grid, it displays details in the second grid - but the check boxes column renders as in the second image: my header render is overwritten with a checkbox, it looks like the checkboxes have been rendered one row above where they should be and the last row is rendered twice.

After some investigation I found that having frozen : true on the checkbox column of the details grid was causing the problem. I use this option with no problem on the master grid. I removed the frozen option and the checkbox column renders properly in the details grid but I would like to use this option in both grids.