LTK example

ltk-first.lisp

(defpackage ltk-first-example
  (:use "CL" "LTK"))

(in-package "LTK-FIRST-EXAMPLE")

(defun gui ()
  (let ((ltk:*debug-tk* t))
  (with-ltk ()
    (wm-title *tk* "Feet to Meters")
    (let ((c (make-instance 'frame)))
      (grid c 0 0 :sticky "ne")
      (grid-columnconfigure *tk* 0 :weight 1)
      (grid-rowconfigure *tk* 0 :weight 1)
      (let* ((c.feet (grid (make-instance 'entry :width 7)
                           1 2 :sticky "we" :padx 5 :pady 5))
             (c.meters (grid (make-instance 'entry :state "readonly")
                             2 2 :sticky "we" :padx 5 :pady 5)))
        (grid (make-instance 'button
                             :text "Calculate"
                             :command (lambda () (calculate c.feet c.meters)))
              3 3 :sticky "w" :padx 5 :pady 5)
        (grid (make-instance 'label :text "feet")
              1 3 :sticky "w" :padx 5 :pady 5)
        (grid (make-instance 'label :text "is equivalent to")
              2 1 :sticky "w" :padx 5 :pady 5)
        (grid (make-instance 'label :text "meters")
              2 3 :sticky "w" :padx 5 :pady 5))))))

(defun calculate (feet-widget meter-widget)
  (setf (text meter-widget) (format nil "~,2F" (* (read-from-string (text feet-widget)) 0.3048d0))))

https://gist.github.com/jasom/4c4bf02e60d85f2644f99ce7be5dce17#file-ltk-first-lisp-L9 helps a lot!

I was in trouble to change the title of the toplevel. I went to create a new toplevel with my preferred title and it spawned two windows!
It was frustating.

Thank you so much for sharing this gist