Maybe someone is interested in a workaround for the postcommand in combobox issue:
(postcommand is a script which will be called right before displaying the pop-down list of choices. This can be used to more dynamically set the list of choices, via the values option. Source: https://tkdocs.com/widgets/combobox.html)
Not really elegant but it solves my problem:
(defun combo-values-when-entering () "Combobox updating values when the mouse enters the widget." (ltk:with-ltk () (let* ((f (make-instance 'ltk:frame)) (outconsole (make-instance 'ltk:scrolled-text :borderwidth 2 :relief :raised :master f)) (c (make-instance 'ltk:combobox :master f :text "Values:"))) (ltk:pack f) (ltk:pack outconsole) (ltk:pack c :side :left :padx 2) (ltk:append-text outconsole "Line 1 (Add more lines here and use the combobox widget thereafter)") (ltk:bind c "<Enter>" (lambda (evt) (declare (ignore evt)) (setf (options c) (cl-ppcre:split #\newline (text outconsole))))))))
(The reading from the textwidget is just an example. In my application I want to read the state of some ports when using the combobox.)
/Volker