Hello Laser,
gx_widget_style_add only adds to existing style settings (i.e. bitwise OR). GX_STYLE_NONE is 0, therefore 2nd call to gx_widget_style_add does nothing (x | 0 = x). You should instead use gx_widget_style_remove(ID_PROMPT, GX_STYLE_DRAW_SELECTED); Also, the first argument needs to be a pointer to the widget control structure, not its ID. You can do ID -> pointer lookup by using gx_widget_find or gx_system_widget_find (as I shown above).
Regards