diff --git a/source_edit.lua b/source_edit.lua
index 606b913..2fc7e1b 100644
--- a/source_edit.lua
+++ b/source_edit.lua
@@ -123,8 +123,10 @@ function edit.check_locs(State)
 end
 
 function edit.invalid1(State, loc1)
-  return loc1.line > #State.lines
-      or loc1.pos > #State.lines[loc1.line].data
+  if loc1.line > #State.lines then return true end
+  local l = State.lines[loc1.line]
+  if l.mode ~= 'text' then return false end  -- pos is irrelevant to validity for a drawing line
+  return loc1.pos > #State.lines[loc1.line].data
 end
 
 function edit.cursor_on_text(State)
@@ -169,7 +171,7 @@ function edit.draw(State, hide_cursor)
       end
       if line.data == '' then
         -- button to insert new drawing
-        button(State, 'draw', {x=4,y=y+4, w=12,h=12, color={1,1,0},
+        button(State, 'draw', {x=State.left-Margin_left+4, y=y+4, w=12,h=12, color={1,1,0},
           icon = icon.insert_drawing,
           onpress1 = function()
                        Drawing.before = snapshot(State, line_index-1, line_index)
@@ -225,7 +227,7 @@ end
 
 function edit.mouse_press(State, x,y, mouse_button)
   if State.search_term then return end
---?   print('press', State.selection1.line, State.selection1.pos)
+--?   print('press', State.cursor1.line)
   if mouse_press_consumed_by_any_button_handler(State, x,y, mouse_button) then
     -- press on a button and it returned 'true' to short-circuit
     return
@@ -268,7 +270,7 @@ end
 
 function edit.mouse_release(State, x,y, mouse_button)
   if State.search_term then return end
---?   print('release')
+--?   print('release', State.cursor1.line)
   if State.lines.current_drawing then
     Drawing.mouse_release(State, x,y, mouse_button)
     schedule_save(State)
@@ -320,11 +322,12 @@ function edit.mouse_wheel_move(State, dx,dy)
 end
 
 function edit.text_input(State, t)
+--?   print('text input', t)
   if State.search_term then
     State.search_term = State.search_term..t
     State.search_text = nil
     Text.search_next(State)
-  elseif State.current_drawing_mode == 'name' then
+  elseif State.lines.current_drawing and State.current_drawing_mode == 'name' then
     local before = snapshot(State, State.lines.current_drawing_index)
     local drawing = State.lines.current_drawing
     local p = drawing.points[drawing.pending.target_point]
@@ -477,7 +480,7 @@ function edit.keychord_press(State, chord, key)
         line.show_help = false
       end
     end
-  elseif State.current_drawing_mode == 'name' then
+  elseif State.lines.current_drawing and State.current_drawing_mode == 'name' then
     if chord == 'return' then
       State.current_drawing_mode = State.previous_drawing_mode
       State.previous_drawing_mode = nil
@@ -490,10 +493,12 @@ function edit.keychord_press(State, chord, key)
         record_undo_event(State, {before=before, after=snapshot(State, State.lines.current_drawing_index)})
       elseif chord == 'backspace' then
         local len = utf8.len(p.name)
-        local byte_offset = Text.offset(p.name, len-1)
-        if len == 1 then byte_offset = 0 end
-        p.name = string.sub(p.name, 1, byte_offset)
-        record_undo_event(State, {before=before, after=snapshot(State, State.lines.current_drawing_index)})
+        if len > 0 then
+          local byte_offset = Text.offset(p.name, len-1)
+          if len == 1 then byte_offset = 0 end
+          p.name = string.sub(p.name, 1, byte_offset)
+          record_undo_event(State, {before=before, after=snapshot(State, State.lines.current_drawing_index)})
+        end
       end
     end
     schedule_save(State)
diff --git a/source_text.lua b/source_text.lua
index fb4c389..4d13748 100644
--- a/source_text.lua
+++ b/source_text.lua
@@ -178,6 +178,7 @@ function Text.text_input(State, t)
 end
 
 function Text.insert_at_cursor(State, t)
+  assert(State.lines[State.cursor1.line].mode == 'text')
   local byte_offset = Text.offset(State.lines[State.cursor1.line].data, State.cursor1.pos)
   State.lines[State.cursor1.line].data = string.sub(State.lines[State.cursor1.line].data, 1, byte_offset-1)..t..string.sub(State.lines[State.cursor1.line].data, byte_offset)
   Text.clear_screen_line_cache(State, State.cursor1.line)