Sets the title of the Window.
The title of a window will be displayed in its title bar; on the X Window System, the title bar is rendered by the window manager, so exactly how the title appears to users may vary according to a user’s exact configuration. The title should help a user distinguish this window from other windows they may have open. A good title might include the application name and current document filename, for example. document filename, for example.
Passing null does the same as setting the title to an empty string.
title of the window