When i invoke a modal operator (it highlights faces under the mouse cursor via raycast and bgl) from the tool shelf, it is running in/for the 3D View, the tool shelf is in but not in other 3D Views displaying the same content.
I need to invoke the modal operator again from the others 3D Views toolshelfs to get the desired effect. Is there a way to invoke it for all 3D Views at once?
Because it is not easy to explain i made a short video (30 sec) to show the problem:
edit: i cannot mark as duplicate but the question was kinda answered here already(it was hard to find for me without the hint from batFINGER):