Fix scrolling with partial lines

* src/xdisp.c (partial_line_height): New function.
(try_scrolling):
* src/window.c (window_scroll_pixel_based): Use it for calculating the
pixel scroll margin correctly in a window with partial lines.

1 files changed, 1 insertions, 0 deletions

diff --git a/src/dispextern.h b/src/dispextern.h
index 51222e636be..eb71a82311c 100644
--- a/src/dispextern.h
+++ b/src/dispextern.h
@@ -3263,6 +3263,7 @@ void move_it_past_eol (struct it *);
 void move_it_in_display_line (struct it *it,
                               ptrdiff_t to_charpos, int to_x,
                               enum move_operation_enum op);
+int partial_line_height (struct it *it_origin);
 bool in_display_vector_p (struct it *);
 int frame_mode_line_height (struct frame *);
 extern bool redisplaying_p;