To set up the comboBox you set width and height just like the scrollpane. When you use the component as a comboBox, the specified height is the height of the combo in expanded form.

The colors are  c [track, bar, button, arrow, background, textPaper, textColor, selTextPaper, selTextColor]

There's also a boxStyle parameter.
boxStyle : 0 = combobox, 1 = listbox

The only difference in functionality is that when using it as a combo, multiple selections are never allowed. When using it as a listbox you can allow multiple selections.
