42S/Free42 programming: jumping back to the last MENU after RTN

[Dave Britten]

Yeah, there are potentially some obscure edge cases where it would cause problems, so a flag to toggle that behavior would probably end up being needed. But it would likely fix more things than it would break if it's limited to only happening when hitting an RTN with an empty return stack while a program has a MENU (or VARMENU?) currently displayed.

Essentially, store a return address any time MENU is called, and make RTN go back there and stop if the return stack is empty and flag 75 is set, so that R/S would begin executing at the step after the MENU instruction. (Programs written to require R/S after working with a menu would need an extra press to get past the STOP following MENU.)