planning out cursor up/down over wrapped lines

README.md

@@ -7,7 +7,7 @@ Known issues:
   implications:
     * A long series of drawings will get silently skipped when you hit
       page-down, until a line of text can be showed on screen.
-    * If there's no line of text at the bottom of the file, one will be
-      created.
-  So far this app isn't really designed for all-drawing files. I'm really just
+    * If there's no line of text at the top of the file, you may not be able
+      to scroll back up to the top with page-up.
+  So far this app isn't really designed for drawing-heavy files. For now I'm
   targeting mostly-text files with a few drawings mixed in.

text.lua

@@ -213,6 +213,7 @@ function Text.keychord_pressed(chord)
     save_to_disk(Lines, Filename)
   elseif chord == 'up' then
     assert(Lines[Cursor_line].mode == 'text')
+    -- previous text line
     local new_cursor_line = Cursor_line
     while new_cursor_line > 1 do
       new_cursor_line = new_cursor_line-1
@@ -228,6 +229,7 @@ function Text.keychord_pressed(chord)
     end
   elseif chord == 'down' then
     assert(Lines[Cursor_line].mode == 'text')
+    -- next text line
     local new_cursor_line = Cursor_line
     while new_cursor_line < #Lines do
       new_cursor_line = new_cursor_line+1