Working with gui-easy tables

table-min.rkt

#lang racket

;; Working with gui-easy tables.


(require
  racket/gui
  racket/gui/easy
  racket/vector)

; Generate a random string of specific length composed of a collection of characters
(define (gen-code alphabet
                  [length 8])
  (build-string length
                (lambda (x)
                  (string-ref alphabet (random 0 (string-length alphabet))))))

; Generate a random data vector
(define (gen-data)
  (build-vector 10
                (lambda (x)
                  (vector (number->string x)
                          (gen-code "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 " (random 4 25))))))

(define sel (obs '())) ;; The actual selection observable
(define shadow-sel (obs '())) ; An observable that temporarily holds the current selection

(define the-data (obs (gen-data))) ; The observable that holds the data of the listbox

;; The table control
(define t-view (table '("IDX" "Content")
                      the-data
                      (lambda (the-event some-data sl)
                        (when (eq? the-event 'select)                          
                          (obs-set! shadow-sel sl) ;; Leave this line in to experience the issue
                          ;;(obs-set! sel sl) ;; Uncomment this line (and comment the above) to experience the workaround
                          ))
                      #:selection sel
                      #:style '(multiple
                                column-headers
                                vertical-label
                                extended)))
                      

(render
 (dialog t-view
         #:min-size '(640 480)))