Type WindowControl

type WindowControl interface {
	Close()
	Hide()
	Show()
	// Frame is the content area in screen coordinates, false when the window
	// cannot say (closed, or not yet placed). It may be called from any goroutine.
	Frame() (ui.Rect, bool)
}

WindowControl is what a Host gives back for a window it opened. All of them are safe to call from any goroutine and act on the event-loop thread.