movingEnabled doesn't seem to have anything to do with dragging the dialogs or controls. Either it has no effect or it has something to do with allowing the player to move.
To enable dragging:
- [Automatic] Make a 3d object, onto which you can paste the 2d dialog components (like the notepad in the map screen). This doesn't seem to work in description.ext dialogs (I've tried it), so, assuming that it isn't just a BIS-only capability, you'd need to put it in an addon.
- [Manual] Capture onMouseButtonDown onMouseButtonUp and onMouseMoving events and move each of the controls yourself.