xdisp.c (set_cursor_from_row): Improve comments.

1 files changed, 12 insertions, 2 deletions

diff --git a/src/xdisp.c b/src/xdisp.c
index c6ae6ad4c14..997c76934d4 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -12606,7 +12606,8 @@ set_cursor_from_row (w, row, matrix, delta, delta_bytes, dy, dvpos)
             }
           if (INTEGERP (glyph->object) && glyph->charpos < 0)
             --glyph;
-          /* By default, put the cursor on the rightmost glyph.  */
+          /* By default, in reversed rows we put the cursor on the
+             rightmost (first in the reading order) glyph.  */
           for (g = end + 1; g < glyph; g++)
             x += g->pixel_width;
           cursor_x = x;
@@ -12683,7 +12684,16 @@ set_cursor_from_row (w, row, matrix, delta, delta_bytes, dy, dvpos)
                 bpos_covered = bpos_max + XINT (chprop);
                 /* If the `cursor' property covers buffer positions up
                    to and including point, we should display cursor on
-                   this glyph.  */
+                   this glyph.  Note that overlays and text properties
+                   with string values stop bidi reordering, so every
+                   buffer position to the left of the string is always
+                   smaller than any position to the right of the
+                   string.  Therefore, if a `cursor' property on one
+                   of the string's characters has an integer value, we
+                   will break out of the loop below _before_ we get to
+                   the position match above.  IOW, integer values of
+                   the `cursor' property override the "exact match for
+                   point" strategy of positioning the cursor.  */
                 /* Implementation note: bpos_max == pt_old when, e.g.,
                    we are in an empty line, where bpos_max is set to
                    MATRIX_ROW_START_CHARPOS, see above.  */