display message down the window’s view hierarchy, thus redrawing all views that need to be displayed, including the frame view that draws the border, title bar, and other peripheral elements.
- macOS 10.0+
This method is useful when you want to modify some number of views and then display only the ones that were modified.
You rarely need to invoke this method.
NSWindow objects normally record which of their views need display and display them automatically on each pass through the event loop.