This is my program. Sign + button is a bit higher than two number buttons on the left. Why ? (in-package :ltk)
(defun make-button (text width height) (make-instance 'button :text text :width width :height height :font "Arial 20"))
(defun calc () (with-ltk () (let ((buttons (make-array '(3 3)))) (dotimes (x 3) (dotimes (y 3) (setf (aref buttons x y) (make-button (format nil "~d" (+ (* 3 x) y 1)) 3 1)) (grid (aref buttons x y) x y))) (grid (make-button "0" 3 1) 3 1) (grid (make-button "+" 3 3) 1 3 :rowspan 2) (grid (make-button "-" 3 1) 1 4) (grid (make-button "*" 3 1) 0 3) (grid (make-button "/" 3 1) 0 4))))