Toolbar icons stacking on each other

I apologize if this has been asked before but I didn’t find anything. I’m having a problem in several projects where the icons in a toolbar over a grid are initially stacked on top of each other. When I pass the mouse over them, they spread back out. This started fairly recently but I don’t know if it is related to our upgrade of the suite to version 2.6 or if it is in my technique. Anyone know the solution?
Jim Dixon

We need the complete sample to reproduce the problem locally.