I think you must mean this dialog:
Possible actions:
1: abort (with core dump, if enabled)
2: normal R exit
3: exit R without saving workspace
4: exit R saving workspace
>
Selection:
It’s not a nice thing to see. It means that R has crashed. You choose one of those items by typing a number between 1 and 4 and then “return”. I got it after starting a vmGUImenu() session and apparently clicking in the wrong place (trying to close a X11 graphics window after the X11 dialog box stopped responding to clicks.) I think this X11 GUI may not be “mature” on the Mac platform.
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solved R: quit !incomplete.cases() function without loosing workspace [closed]