file load:
  cursor_line = 1
  first line is a drawing -> cursor_line = 2
click on text -> cursor moves
click on first character of text -> cursor on first character of text
click to right of text -> cursor past end of line
click to right of wrapped text -> cursor on final character of line
click on drawing -> cursor doesn't move
cursor past end of line -> renders
create drawing -> cursor bumps down below drawing
backspace
  cursor_pos == 0, previous line is a drawing -> delete drawing, cursor still visible at start of line
  cursor_pos == 0, previous line is text -> join lines, cursor still at same character

enter
  cursor_pos == 0 -> insert empty line above current line