Disabled state is not shown (opacity 40%) if opacity was changed.

In attached project:
Change disabled state using toggle button. You see, that opacity is chaged. Also button is disabled.
Change opacity using slider.
Try to change disabled state using the toggle button. You will see, that opacity is not changing any more. (but disabled state of control is still working right)

Notion : Also this is actual, if slider would be unbinded. (there isno any influence on opacity)