Behavior in the 2017 wikitext editor:

• Press Command–Enter in the edit summary field.
• Page is saved.

Behavior in the 2010 wikitext editor:

• Press Command–Enter in the edit summary field.
• Page is not saved. A second copy of the editing window is opened in another tab.

Request:
Make them match. Command–Enter should save the page in both editors. Ideally, Command–Enter would not save the page if pressed in the main editing window (because it's possible that people expect it to do other things there, e.g., a soft return [which is normally Control–Enter, but if you don't remember the details on the first try...]).