appkit:panel

(appkit:panel window &key (x 20) (y 20) (width 100) (height 100) fill (radius 0) (border 0) border-color)

Adds a filled rectangle -- an NSBox in its custom form, optionally rounded and bordered -- to the window's content view and answers it. Coordinates are AppKit's: the origin is the window's bottom-left corner. Its colour is changed with appkit:set-color and it answers a click through appkit:on-click, so a panel is the tile a board game is built from. Part of the appkit package, a Cocoa widget layer written in rontolisp over objc and loaded on first use: macOS (java -jar, the rontolisp binary, or a compiled .class / .jar; never a .wasm), with a display. See the macOS GUI guide.

CL-USER> (defvar *tile*
    (appkit:panel *win* :x 20 :y 20 :width 34 :height 34
                  :fill (appkit:color 104 116 146) :radius 7))
CL-USER> (appkit:set-color *tile* (appkit:color 230 233 241))
#<objc _NSTaggedPointerColor>