Improve scrolling when line-spacing != 0 and scroll-step = 1.
lisp/simple.el (default-line-height): New function. (line-move-partial, line-move): Use it instead of computing the line height inline. (line-move-partial): Always compute ROWH. If the last line is partially-visible, but its text is completely visible, allow cursor to enter such a partially-visible line.
Showing with 55 additions and 37 deletions