There are people who like using a single main window with multiple tabs.  There are people who like using multiple main windows from one process.  There are people who like using multiple processes.  There are people who use combinations of those schemes. All of these scenarios have advantages: * Multiple tabs works well on small displays, and avoid exploding task bar sizes. * Multiple windows from the same process lets you create windows from within the application, and lets you close down the whole application when you're ready to. * Multiple processes provide crash isolation and allow processing in parallel, and work better in scripts. * Combinations allow for complex workflow/desktop layouts. None of them is wrong, and for all of them the users who like them will be understandably annoyed if their option gets taken away.  Breaking any of them should require a really good rationale, and "I don't understand how you can work with that configuration" is not a good rationale.  Don't use a configuration that you don't like.

On macOS, OpenSCAD behaves like most Mac applications: one ordinarily runs a single instance of the app, and that instance handles double clicking on .scad files, or opening .scad files in the Finder. It is possible to run multiple simultaneous instances from the command line, with commands like: $ /Applications/OpenSCAD.app/Contents/MacOS/OpenSCAD & $ /Applications/OpenSCAD.app/Contents/MacOS/OpenSCAD & and *Quit ⌘Q* from the menu bar quits that just instance (and all of its windows) and leaves the other ones running. I'm requesting that whatever decision you make for Windows and Linux you leave the macOS behavior untouched. On Mon, May 25, 2026 at 11:53 PM John Found via Discuss < discuss@lists.openscad.org> wrote: > Hi all. > > Reading (well in github I am in read-only mode) the discussion about by > PR (https://github.com/openscad/openscad/pull/6838) want to add my > thoughts on the subject. > > Actually I realized that File|Quit (Ctrl+Q) closes all running > instances of OpenSCAD reading the posts in the discussion. > > But such a feature actually contradicts to the "principle of > least astonishment" and should not exists at all. Closing all instances > from one of them is very strange behavior that looks like a crash of > the application. Especially if there is no file changes and the > windows close silently in background. > > Of course, opening new windows is OK - Happens exactly what the user > explicitly requested. > > In addition, closing all windows creates different strange behavior > issues. The window state save problems is only one of them. For example > it first closes the editor windows and only then asks for saving. > If you select "Cancel" it actually not cancels, because the editor > window is already closed. And it not saves either. > > So, IMHO, the best solution for all these problems is to actually merge > the functionality of File|Quit and File|Close and close only one window > at a time. > > Best Regards > John Found > _______________________________________________ > OpenSCAD mailing list > To unsubscribe send an email to discuss-leave@lists.openscad.org >

On Tue, 26 May 2026 18:32:51 +1000 "Michael Marx (spintel) via Discuss" <discuss@lists.openscad.org> wrote: > That hinges on the understanding of "all running instances". > On Windows & Linux (don't know Mac), you can run (ie start up) many instances. > Each is a separate process. > That is different to having multiple windows emanating from one process. > > AFAIK (usually) applications only manage the windows that are part of the one process. > That is ending the process, closes all windows. > But doesn't directly* affect windows of the same application running as a separate process. > * things like saving options/layout could indirectly affect other processes. > > On that basis, File/Quit closes the managing process, and thus all windows associated. > But it does NOT close windows owned by another instance of the same application in another process. > > That is standard behaviour. Depends on the windows app and version of the week. Modern excel runs as one instance in all cases, you only think you are creating new instances of excel because Microsoft chose to make that specific app turn your request for a new instance into something else. It's a quirk of some windows apps (and you'll find the same quirk in some apps on other platforms too) Alan