racket-tray/README.md

racket-tray

A small system tray API for Racket.

Version 0.1.1 implements Windows directly through the Win32 API. It uses the native HWND of an existing Racket frame% or dialog%, Shell_NotifyIconW, and SetWindowSubclass. No additional native DLL is required.

#lang racket/gui

(require racket-tray)

(define tray-frame%
  (class frame%
    (super-new [label "Tray example"]
               [width 400]
               [height 250])

    ;; Close [X] to the tray instead of destroying the frame.
    (define/override (on-close)
      (send this show #f))))

(define frame (new tray-frame%))

(define (show-frame)
  (send frame show #t)
  (when (send frame is-iconized?)
    (send frame iconize #f)))

(define tray
  (mk-tray frame
           "example.png"
           show-frame
           #:hide-on-minimize? #t))

(tray-set-menu!
 tray
 (list
  (list "Open" show-frame)
  'separator
  (list "Exit"
        (λ ()
          (tray-close tray)
          (exit)))))

(send frame show #t)

mk-tray and tray-set-icon! accept both Windows .ico files and .png files. PNG transparency is preserved when the image is converted to a native Windows tray icon.

With #:hide-on-minimize? #t, minimizing the associated window hides it from the taskbar while keeping its native window handle alive. Closing a window to the tray does not need a separate tray API: override frame%'s on-close and call (send this show #f).

tray-set-menu! accepts a popup-menu% object directly, a simple menu list, or #f to remove the context menu.

At the moment non-Windows platforms report that the operation is unsupported.