amend cursor.sml's 'helpTillNextChr' function to work with new line break scheme, and use it to implement 'delete till' functionality starting with 'dt' (for example, 'dta' deletes till 'a', 'dts'detetes till 's', etc.)

fcore/app-update.sml

@@ -432,7 +432,7 @@ struct
     else
       let
         val buffer = LineGap.goToIdx (cursorIdx, buffer)
-        val otherIdx = fMove (buffer, cursorIdx, chr)
+        val otherIdx = fMove (buffer, cursorIdx, chr) + 1
 
         val low = Int.min (cursorIdx, otherIdx)
         val high = Int.max (cursorIdx, otherIdx)
@@ -574,7 +574,13 @@ struct
       case String.sub (str, strPos + 1) of
         #"t" => 
           (* todo: delete till chr, forwards *)
-          clearMode app
+          (case newCmd of
+            CHAR_EVENT chr =>
+              deleteToChr (app, 1, Cursor.tillNextChr, chr)
+          | KEY_ESC =>
+              clearMode app
+          | RESIZE_EVENT (width, height) => 
+              resizeText (app, width, height))
       | #"T" => 
           (* todo: delete till chr, backwards *)
           clearMode app
@@ -662,9 +668,6 @@ struct
             CHAR_EVENT chr => handleChr (app, count, chr, str)
           | KEY_ESC => clearMode app
           | RESIZE_EVENT (width, height) => resizeText (app, width, height)
-        else if numLength + 1 < String.size str then
-          (* continue parsing. *)
-          parseAfterCount (numLength + 1, str, count, app, newCmd)
         else
           (* continue parsing. *)
           parseAfterCount (numLength, str, count, app, newCmd)