Want arrow key functionality in Tedit and Sedit -- should copy TTYIN

[masinter]

TTYIN supports cursor movement by keyboard commands. issue #58 covers the inconsistency of key bindings, but even with consistency and code assignment, we're still missing cursor treatment in two of the editors: SEdit and TEdit.

I'll raise this as a separate issue because it seems to be a show-stopper for some:

https://journal.paoloamoroso.com/stringscope-a-string-listing-tool-in-interlisp

[pamoroso]

Arrow key functionality was added to TEdit and the TTY editor and is probably less necessary in SEdit, so I'm closing this issue.

[masinter]

Enabling arrow keys in SEdit would be a useful addition, even if not as urgent. One problem is there is some subtlety about how cursor keys should work around parentheses. T

he caret can be

• inside a word, LISP^WORD
• at a word beginning ^LISPWORD
• at a word end LISPWORD^
• in between parentheses SEXPR)^))) or SEXPR)^ (
• there are keystrokes which in some situations wind up just moving the cursor (right paren?).
• There are some cases where there are two positions between two characters, e.g. when inserting a space.