I implemented SLIME REPL integration for CommonQt some time ago,
don't know whether it still works in recent CommonQt/SLIME versions, see
https://github.com/commonqt/commonqt/blob/master/repl-integration.lisp
It utilizes SLIME REPL eval hooks to make SLIME REPL evaluate
expressions in the context of GUI thread, which is much safer
than just starting separate thread and hoping that doing stuff in
the main thread will not cause some kind of race condition.
When it worked it was enough to do
(ql:quickload 'qt-repl)
(qt-repl:start-gui-thread)
And after that you could do most GUI stuff right from REPL
without worrying that something will break.
In my not-up-to-date CommonQt fork it still works, at least when using
CCL: https://github.com/ivan4th/commonqt

On Tue, Dec 29, 2015 at 1:11 AM, Stas Boukarev <stassats@gmail.com> wrote:
On Tue, Dec 29, 2015 at 1:08 AM, Orm Finnendahl
<orm.finnendahl@selma.hfmdk-frankfurt.de> wrote:
> Am Dienstag, den 29. Dezember 2015 um 00:54:09 Uhr (+0300) schrieb Stas Boukarev:
>> All the GUI stuff has to be done from the same thread (and on some
>> OSes it has to be the main thread).
>> To communicate with Qt from a different thread use Qt signals, they
>> are thread-safe.
>
> Thanks, that helps! Do you know, why it is impossible to restart the
> tutorial example after the thread has finished?  Restarting in the
> main thread after closing the window is no problem. The only way to
> restart the tutorial after running it within sb-threads:make-thread is
> to restart sbcl.
You can restart it in that thread, but only in that thread. The event loop
cannot be restarted, but as long as it's running you can execute and close
as many windows as you'd like.

--
With best regards, Stas.




--
Ivan Shvedunov <ivan4th@gmail.com>
;; My GPG fingerprint is: 2E61 0748 8E12 BB1A 5AB9  F7D0 613E C0F8 0BC5 2807