Ok, big question. I am using an MFC class CComboBox, which resembles a basic ComboBox control. It works fine, but when I try to show that dropdown list thing, it's only 1 pixel wide. I've tried everything, and it's no use. P.S. I think the problem might be with the resource(I use VC 6.0), because when I click on that test button in the resource editor, the dialog shows up, and the combo box has the same problem, the list is only 1 pixel wide.
How big is your combo box drawn on your resource editor? Unless you've hit one of the more obscure checkboxes on its properties, it should show up the size you drew it. I am of course making the assumption here that you are using the resource editor... some people don't.
A common problem is having a combo box in which the dropdown list is only one pixel high. In the resource editor select the combo box and click on it's little dropdown button (the arrow on the right side). This will allow you to size the actual dropdown list instead of the combo box. I know you said wide, but this is the only thing I could think of.