Buttons seem to work only below or above vertical center

Steps to reproduce:

• create/open a project
  EITHER
• just switch to Debug view and hover across some of the debugger buttons (Continue, Stop, Step Into, Step Over,..)
  OR
• place some hittable breakpoints
• build & start debugging
• when stopped at a breakpoint hover across some of the debugger buttons (Continue, Stop, Step Into, Step Over, ..)

Current result:

• if cursor is placed at vertical center ( ? ± some pixels above/below ) of the button the hover highlighting of the button disappears and the button is not clickable
• if cursor is placed above/below vertical center of the button it is highlighted as hovered and clickable