My own answer:

I find it highly unusual and never expect to close something with
Cmd-s. Outside of Squeak I know about pressing Enter/Return on a main
text entry, or even the space bar if it is a button, to close a
dialog. But not "save = close".

But it seems like this used to (or should?) work to save an image, and
I also got a ticket in Squot to add this behavior to the commit
dialog.

That's why I would like to know how much of a Squeak interaction idiom
this really is, where does it come from, and what other systems
exhibit this behavior?

Am Fr., 31. Juli 2020 um 16:03 Uhr schrieb Jakob Reschke
<forums.jakob at resfarm.de>:
>
> Hi all,
>
> Under which circumstances do you expect that the "accept" action and
> more specifically pressing Cmd-s _close_ a dialog window or whatever
> thing you have been entering text in?
>
> Kind regards,
> Jakob
>
>
>
> Am Fr., 31. Juli 2020 um 10:13 Uhr schrieb Marcel Taeumel
> <marcel.taeumel at hpi.de>:
> >
> > And: Looking at the current implementation of FileSaverDialog, that "unaccepted changes"-triangle is used to let the user type in a file name and only after [cmd+s] check whether that name has the required suffix. [return] or [enter] both combine that behavior with a final accept-and-close in the dialog.
> >
> > So, [cmd+s] is not intended to close the dialog. Just type in and hit [enter] or [return]. That is implemented via an event filter and works fine in Squeak 5.3 on Windows 10, too.
> >
> > Yes, it would be possible the change the implementation to let [cmd+s] also close the dialog.
> >
> > No, it is actually unrelated to the preference "mouse over for keyboard focus". Something else is going on in your image or platform. :-)
> >
> > Best,
> > Marcel
> >
> > Am 31.07.2020 09:55:27 schrieb Marcel Taeumel <marcel.taeumel at hpi.de>:
> >
> > Hi Tim,
> >
> > Windows 10 here. Works for me in recent Trunk (Build 19801) with [return]. Does not work with [cmd+s]. "Mouse over for keyboard focus" enabled, of course. ;-)
> >
> > Best,
> > Marcel
> >
> > Am 31.07.2020 06:31:07 schrieb Tim Johnson <digit at sonic.net>:
> >
> > Hi all,
> >
> > In 5.3, when using the World menu, "Save as...," on macOS / OS X, with focus-follows-mouse[1] turned on, I enter my new file name, and when I press return or Cmd-S, the dialog does not go away. (Even if I leave the mouse focus in that input field.) My "changes are accepted," so to speak (the orange triangle goes away), but the image is not saved and the dialog does not go away. It seems like I still have to go click "accept".
> >
> > I think in every previous version of Squeak I've used, in the dialog that appears upon choosing World menu -> "save as...", I can just type the new name and hit return or Cmd-S and the dialog will go away and the image will be saved.
> >
> > With focus-follows-mouse turned off, 5.3 works as intended: enter/return dismisses the dialog and the image is saved with the new name.
> >
> > Wondering if this can be categorized as a regression[2]. To verify, I just tested in 5.2. Indeed, in 5.2, whether focus-follows-mouse is turned on or off, I can enter a new file name and press enter/return and the image will be saved under the new name. I don't have to move my mouse to click the "accept" button.
> >
> > Could this somehow related to any other issues with where keyboard focus and/or events are going? (Specifically talking about how entire windows are refreshing with every keypress into a code pane, for example.)
> >
> > Thanks,
> > Tim
> >
> >
> > [1] Preferences valueOfFlag: #mouseOverForKeyboardFocus
> >
> > [2] regression meaning: since I care, I have to fix it? :) Or, regression meaning: I file a bug in Mantis? :)
> >
> >
> >
> >