GUI: Dialog redraw

I have a dialog which subclasses Operator and then overrides draw().

On the dialog is a combo which after changing the value I need the dialog to be redrawn, just as a panel does automatically.

I’ve tried calling it, but don’t know how to just do a redraw…
bpy.ops.object.dialog_operator(‘INVOKE_DEFAULT’)
bpy.ops.object.dialog_operator(‘EXEC_DEFAULT’)

Another idea I have just struck on is try and put a panel into the dialog box, but pondering on bl_space_type and bl_region_type, say “VIEW_3D” and “TEMPORARY”

Anyway, getting late so I may leave this conundrum until tomorrow, but any suggestions welcome!