Automatic migration. Original reporter: "fedyakin"
If the root window is not active when it is clicked on, the Window::moveToFront_impl will return true, causing the handled count to be 2 on the return from Window::onMouseButtonDown in GUISheet::onMouseButtonDown. The updateMouseEventHandled function decrements the handled count by one if mouse pass through is enabled. This results in a handled count of one, and reporting that the input was used.
It seems like updateMouseEventHandled should set e.handled to 0, not decrement it.