Depends what you're doing with the combobox. We use a
combobox for doing row filtering in our datagrids. We don't create
a sticky first row though...we extend AdvanedDataGridHeader and
include the combobox as part of the column header.
If you really want it as a grid row, however, what I would do
is extend whatever class you're using as your grid's dataProvider,
and override the addItem, addItemAt, removeItem, etc., methods so
that they never remove the sticky row from the dataProvider. Then
you can use the grid's rendererProviders property to create
specific renderers for that row.