I have a 3-pixel left margin for a left-aligned, non-editable combo box field. The margin is ignored (data shifts to the left) if I set the field to readOnly:
forms.elements.comboxfield.readOnly = false //data correctly positioned based on margin setting
forms.elements.comboboxfield.readOnly = true // data shifts to left, ignoring left margin setting.
Yes. If the combobox is editable, the margins are preserved when programatically setting it to readOnly. The problem only manifests if the combobox is non-editable.