Right approach to change materials of actors by widget

I have set up a test cube now and set the click event on Left mouse button.
It prints a string selected when clicking the cube and unselected when clicking other actors in the scene. So that works…

Still can’t get change the colours, the widget is set on always showing, and I have set 2 colours in the widget on hovering, but it doesn’t work. Maybe there is no mouse activity in the widget? I play the level in Selected Viewport mode.

I had set a SelectedActor variable in the LB and also in the TestCube BP. Set on the actor Testcube variable type. Or is that not necessary to do it also in the TestCube BP? Or is it not working correctly when having those 2 variables?