TEXT

Here's an example that works with more than 255 characters in a field.

WINDOW 1
ed$ = "Hello Al." + CHR$(13) + "You're the greatest!"
ed$ = ed$ + CHR$(13) + "Thanks for sending this."
ed$ = ed$ + CHR$(13) + CHR$(13) + "Press mouse to continue."
EDIT FIELD 1, ed$, (10,10)-(200,300)
WHILE FN BUTTON = 0
 HANDLEEVENTS
WEND

dum$ = ""
nlines = 0
GET FIELD txtH&, 1
LineWeWant = 2                                    ' this is the line of text to grab

LONG IF txtH&
 osErr = FN HLOCK (txtH&)
 size& = FN GETHANDLESIZE(txtH&)
 nlines = 1
 FOR X = 2 TO size& - 1
  dum$ = CHR$(PEEK([txtH&]+ X))
  LONG IF dum$ = CHR$(13)
   nlines = nlines + 1
   LONG IF nlines = LineWeWant + 1
    X = size&
   XELSE
    textArray$ = ""
   END IF
  XELSE
   textArray$ = textArray$ + dum$
  END IF
 NEXT X
 osErr = FN HUNLOCK (txtH&)
 DEF DISPOSEH(txtH&)
END IF

EDIT FIELD CLOSE 1
DELAY 500
CLS
PRINT "Line " LineWeWant " = ";
PRINT textArray$
PRINT : PRINT "----------"
INPUT "Press RETURN to end"; X$
END

See if this will do what you want. I think it's a little more direct than some of the other approaches suggested. It may be buggy, as it just oozed off the top of my head, but it should be close.

I didn't go into great length documenting what this does--If it doesn't make sense to you, please ask.

LOCAL FN get1Line$(editFieldID,line2Get)
  teH& = TEHANDLE(editFieldID)
  SELECT
    CASE line2Get < teH&..teNLines
      nextLine = {[teH&]+_teNLines+line2Get+line2Get+2}
    CASE line2Get = teH&..teNLines
      nextLine = teH&..teLength%+1
    CASE ELSE
      BEEP
      PRINT "There is no line";line2Get;"."
      foundLine$ = "ERROR"
      EXIT FN
  END SELECT
  lineOffset = {[teH&]+_teNLines+line2Get+line2Get}
  lineLength = nextLine - lineOffset-1    'omit CR
  IF lineLength > 255 THEN lineLength = 255
  POKE @foundLine$, lineLength
  BLOCKMOVE [teH&..teTextH&]+lineOffset,@foundLine$+1,lineLength
END FN = foundLine$