UPDATED

To indicate that the button opens another dialog box, use an ellipsis ( ... ), such as Info....
In addition to text and image buttons, settings can be changed with check boxes (toggle tiles) and
radio buttons (radio_button tiles), as described next.
Making Buttons Work
OK and Cancel are easy, because their functions are already defined. It’s one thing to populate a
dialog box with buttons; it’s another to have them execute commands.
Let’s see how to make buttons execute commands. In the tutorial, you create a dialog box with Plot
and Preview buttons. The figure below shows how it will look in Linux; it looks similar in Windows.
The purpose of the Plot button is to execute the Plot command, and of Preview button to execute
the Preview command.
The easy solution would be to add an action attribute to each button to execute a LISP function,
such as (command "plot"). But we cannot, because DCL does not allow the highly-useful command
function to be used in the action attribute!
The key to solving the problem is the key attribute. It gives buttons identifying names by which
LISP functions can reference them, such as:
key = "plot";
Then, over in the LISP file, you use the action_tile function to execute the Plot command. Well,
not quite. It has the same restriction against use of the command function, so you must approach
this indirectly by getting action_tile to refer to a second LISP routine, such as (action_tile "plot"
"(cmd-plot)").
But even this will not work, because you need your custom dialog box to disappear from the screen,
and be replaced by the Plot dialog box. The solution is to become even more indirect:
(action_tile "plot" "(setq nextDlg 1) (done_dialog)")
"plot" — identifies the Plot button through its key, "plot".
(setq nextDlg 1) — records that the user clicked the Plot button for further processing later on.
(done_dialog) — closes the dialog box.
This is done twice, once each when the user clicks the Plot button or the Preview button. The Preview
button’s code is similar; changes are shown in boldface:
(action_tile "preview" "(setq nextDlg 2) (done_dialog)")
22 Designing Dialog Boxes with DCL 391