DataGridView Combobox flicker issue

I have attached a sample application  for this issue.  When we have a data grid and it has a combobox column in it we want the combobox to popup when they click on the cell.  I have added the event CellMouseClick and force the drop down to show and it seems to work but the screen flickers and places the dropdown in the upper left of the screen and then shows where it should under the column.

I am using 1.5.9 and same behavior happens in 1.5.6 on another developers machine.

Thanks -Tim