A Boolean value that indicates whether the window can become the key window.
The value of this property is
true if the window can become the key window, otherwise,
Attempts to make the window the key window are abandoned if the value of this property is
false. The value of this property is
true if the window has a title bar or a resize bar, or
Managing Key Status
var isKeyWindow: Bool
A Boolean value that indicates whether the window is the key window for the application.
Moves the window to the front of the screen list, within its level, and makes it the key window; that is, it shows the window.
Invoked automatically to inform the window that it has become the key window; never invoke this method directly.
Invoked automatically when the window resigns key window status; never invoke this method directly.