Simplifying the code is always better but the main reason to keep the native dialogs on win/mac was that they caused Blender to get focus (if you were closing from a taskbar or another screen for instance). Is this drawback acceptable?

Ah, well then I'll check on adding a GHOST API function to bring a window into focus.

While i'm not on the UI team, i am on the windows platform team. and i'm pretty sure i brought this up in the previous review. However the ui guidelines for dialog boxes has the following recommendations.

• Right-align commit buttons in a single row across the bottom of the dialog box, but above the footnote area. Do this even if there is a single commit button (such as OK).
• Present the commit buttons in the following order:
  • OK/[Do it]/Yes
  • [Don't do it]/No
  • Cancel
  • Apply (if present)
  • Help (if present)

App	Quit Dialog	Comment
Blender		Bad:Order is different , buttons are split between left aligned and right aligned
Blender		Bad: same
Office		Bad: Buttons are not right aligned.
Paint		as expected.
VisualStudio		As Expected.

to take full advantage of muscle memory of users on this platform I STRONGLY recommend changing it from

Save changes to "xxxxxx" before closing?
Cancel                     Discard Changes / Save & Quit

to

Do you want to save changes to "xxxxxx" ?
                             Save / Don't Save / Cancel

However i'll let the UI team have the final say on this.

In D3118#74108, @Ray Molenkamp (LazyDodo) wrote:

to take full advantage of muscle memory of users on this platform I STRONGLY recommend changing it from

Save changes to "xxxxxx" before closing?
Cancel                     Discard Changes / Save & Quit

to

Do you want to save changes to "xxxxxx" ?
                             Save / Don't Save / Cancel

However i'll let the UI team have the final say on this.

Can we agree on:

• Windows follows Microsoft guidelines
• macOS follows Apple's Human Interface Guidelines (similar to Blender's built-in, cancel on left, save on right)

Linux doesn't have guidelines per se, each desktop environment sets their own, so I'd keep the same layout as now, since it matches the quit dialogs on Krita, GIMP, Inkscape and similar tools Linux artists are used to.

seems reasonable enough, and it will be familiar for window/mac users.

Here's what it looks like:

Windows
macOS & Linux

What's still missing is the "Save" button being highlighted. We don't have a mechanism for that in the UI code currently, but would be good to support it here since I guess some might be used to quick Ctrl+Q -> Enter...