Fix and document components of mouse event position.

 src/keyboard.c (make_lispy_position): Put a meaningful value in yret
 when the click is on the header or mode line.
 doc/lispref/commands.texi (Click Events): Document the values of X, Y and
 COL, ROW in the event's position, when the click is on the header or
 mode line, on the fringes, or in the margins.

2 files changed, 9 insertions, 3 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 61ef9a202a8..eac550a7334 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,8 @@
+2010-11-26  Eli Zaretskii  <eliz@gnu.org>
+
+        * keyboard.c (make_lispy_position): Put a meaningful value in yret
+        when the click is on the header or mode line.
+
 2010-11-25  Eli Zaretskii  <eliz@gnu.org>
 
         * xdisp.c (set_cursor_from_row): Don't forget to consider the
diff --git a/src/keyboard.c b/src/keyboard.c
index e96d0167fd4..923ac1ad1d9 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -5283,9 +5283,9 @@ make_lispy_position (struct frame *f, Lisp_Object x, Lisp_Object y,
           xret = XINT (x) - window_box_left (w, TEXT_AREA);
           yret = wy - WINDOW_HEADER_LINE_HEIGHT (w);
         }
-      /* For mode line and header line clicks, return X relative to
-         the left window edge; ignore Y.  Use mode_line_string to look
-         for a string on the click position.  */
+      /* For mode line and header line clicks, return X, Y relative to
+         the left window edge.  Use mode_line_string to look for a
+         string on the click position.  */
       else if (part == ON_MODE_LINE || part == ON_HEADER_LINE)
         {
           Lisp_Object string;
@@ -5305,6 +5305,7 @@ make_lispy_position (struct frame *f, Lisp_Object x, Lisp_Object y,
             ? PT : XMARKER (w->pointm)->charpos;
 
           xret = wx;
+          yret = wy;
         }
       /* For fringes and margins, Y is relative to the area's (and the
          window's) top edge, while X is meaningless.  */