On macOS, Command-M simultaneously minimizes the window and opens the "Open Module..." dialog. This happens with a very confusing sequence of visual effects (see attached animated gif).

This doesn't happen when activating either of the menu items; only when using the keyboard shortcut.

Tested with current master (3.8.0a0, 53835e92d3).

What I see in the .gif is that Open Module is open on top of Shell (not minimized, traffic lights gray) and that clicking Cancel closes Open Module and temporarily minimizes Shell, before it pops back up with traffic lights.  It is hard to imagine that how one opens Open Module changes its close behavior.

With 3.7.1rc1, with unreleased tk patches, Command-M immediately after opening IDLE (Shell) closes IDLE.  A window pops up offering to send a report to Apple, or to re-open.  'Re-open' does not work.  After opening another window, I see Shell minimize and pop back with the traffic lights gray.  Both Cancel and Escape have the effect in the gif.  Clicking OK with a valid module name does the same and opens the module.

In summary, using Command-M either crashes IDLE or causes the change in traffic lights to be accompanied by minimizing and restoring.

Kevin, another weird tkinter/tk Mac behavior.

AFAICT, the problem here is that there is a duplicate command accelerator assignment: IDLE assigns CMD-M to its Open Module command (https://github.com/python/cpython/blob/master/Lib/idlelib/config-keys.def#L205) but either Tk or the underlying macOS services it uses already use CMD-M to mean "minimize the front window to the Dock" (https://support.apple.com/en-us/HT201236).  You can see in the IDLE menu bar where CMD-M shows up in the Window menu stack (with Minimize) but not in the the File stack (where Open Module is).  Since CMD-M has a commonly used system-wide meaning, it would probably be best to change IDLE's Open Module to use something else.

I agree with Ned's analysis. The shortcut for macOS should be changed, or simply removed if there's no good candidate for a shortcut.

Terry, what do you suggest?

I routinely use Alt-M to open modules on Windows, so I would want a shortcut on Mac also.  I just made a 'Mac-module' custom keyset with Control-Key-M for open-module, and it works.  It that acceptable?

We do not usually change default keysets, but this amounts to a bugfix in relation to current MacOS.  I would add it to the IDLE section of What's New.

Ned, is the system use of CMD-M newer than IDLE's (15 years?)?

> is the system use of CMD-M newer than IDLE's (15 years?)?

macOS has been using CMD-M for minimize for quite a while.  It's listed in the current Apple "Human Interface Guidelines" which is the reference document that Apple itself and third-parties are strongly encouraged to follow (sort of the PEP 8 for macOS UIs).  It's probably a good idea for anyone working on the IDLE UI to read through the macOS section at least once.

Note that they discourage the use of the Control key as a modifier and they also encourage the use of the Shift key as a secondary modifier "when a shortcut complements another shortcut".  Following those suggestions, perhaps a better choice for "Open Module" would be Shift-Command-O (complementing "Open File" Command-O), if it isn't already being used by IDLE.

https://developer.apple.com/design/human-interface-guidelines/macos/user-interaction/keyboard/

Indeed Command-M has been in use for a while.

+1 for Shift-Command-o. I don't see it used in the default key config (Lib/idlelib/config-keys.def).

We already use Shift-Command-s for "Save As...", so this would be a consistent use of a Shift-Command modifier.

I like the idea, but for me, Shift-Command-o does the same as Command-o -- open file, and setting open-module to shift-command-key-o does not override this.

Terry, does Shift-Command-s trigger "Save" or "Save As" for you? If "Save As", then surely this is something that can be worked out?

#21359, reported by Ned in 4/2018, is about "Cmd-Shift-Z, has the same effect as the Undo accelerator, Cmd-Z"  So there may be a general problem with Cmd-Shift == Cmd.

That's a good point. I see that Cmd-Shift-S which is defined as the shortcut for "Save As.." seems to have the same effect as Cmd-S "Save".  Also, the Cmd-Opt-S shortcut for "Save Copy As.." seems to bring up the save dialog window twice, the second after the first closes.  I guess somebody should go through and try to see exactly which Tk events IDLE is seeing in these cases similar to what Ronald was doing while investigating Issue11055 (referenced in Issue21359).

I am closing this as a duplicate of #21359 as I believe there is at least one more non-working shortcut and because I believe the solution is to test all and patch the default mac keyset all at once.