I guess this question relates to the behavior of ti-menu-load-string inside a Scheme definition.

This trivial example works (it closes a graphics window):

(ti-menu-load-string "/display/close-window 1")

and it also seems to leave a boolean as its result.

But this doesn't:

(define shell (ti-menu-load-string "/display/close-window 1") )

(shell)

It closes the graphics window then gives this error and dies:

Error: eval: invalid function

Error Object: #t

I think the Scheme eval procedure is choking on the boolean that ti-menu... returns, and somehow I need to eliminate it, but that's just a guess.

Big thanks for any help for this new user!

Whoops - found it - I should have said

(define (shell)... instead of

(define shell ....

Just a newcomer's mistake.