Returns a value which indicates how the top level interface is displayed.
capi
top-level-interface-display-state interface => display-state
| interface⇩ | 
A top level interface or dialog window. | 
| display-state | 
One of  :normal,:maximized,:iconic,:hiddenor:full-screen. | 
Top level interfaces and dialogs can be manipulated by the user, such as being iconifed or maximized. The program can manipulate these windows too. The generic function top-level-interface-display-state returns a value that indicates the current state of the interface interface. The following values can be returned:
| :normal | 
The window is visible and has its normal size. | 
| :maximized | 
The window is visible and has been maximized. | 
| :iconic | 
The window is visible as an icon. | 
| :hidden | 
The window is not visible. | 
| 
The window is full screen (only supported on macOS 10.7 and later). This value is only applicable when the window-styles list contains the keyword  | 
These values can also be passed as the :display-state initarg when making a top level interface.
In addition, the function (setf top-level-interface-display-state) can be used to change the state of a top level interface. The value can be set to one of the above, or to :restore if the current state is :iconic or :hidden. When set to :restore, the state will become :normal or :maximized depending on how the interface was visible in the past.
top-level-interface-p
top-level-interface-geometry
set-top-level-interface-geometry
interface
7 Programming with CAPI Windows
CAPI User Guide and Reference Manual (Unix version) - 01 Dec 2021 19:32:42