Another trick is: The combobox has too heights: The height of the edit box and the button (this only depends on the font of the edit) and the height of listbox. Normally the listbox has a height of 3. so you may add items but they are not shown. If so click the button of the combobox in the resource editor, then resize it again. This helps to resize the listbox of the combobox.
Was that what the problem was?
