comboBox Colour

I have a form with 5 rows of contorls on it.

Each row has a 2 textboxes and a combobox.

When the i change rows i want to set the back-colour of the selected row to white and all of the other rows to grey.

However, when i do this the combo box is not repainted properly, and only where there is text in the drop down bit is the colour white, the rest is still grey.

Any ideas welcome.

Cheers,

Iain.