The TCDIALOG is not always function complete. If its output could be copied to the clipboard or pushed to the top of the command stack (like Ctrl-K), then it could be recalled and supplemented before execution.
Since the user can only discover that TCDIALOG doesn't cover all options while in the dialog, my original suggestion of an option /N has the wrong form.
Request 1: Add the command itself to the edit control
Request 2: Add a button to copy the contents of the edit control to one of the following:
also closing the dialog without execution.