$dbuw/$dbuh use GetDialogBaseUnits() which are the average width/height of the system font.
The -l/map options use MapDialogRect() which takes a window handle and bases its calculation on the font being used by a dialog, which can vary by system, language, application, etc.
So these can be added but they would have to be added as $dialog().mapw/.maph properties and can only be used once the dialog has been created using /dialog, eg. in the on dialog init event.
