(construct_mouse_wheel): Handle negative coordinates.

2 files changed, 6 insertions, 2 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index c47d5970fad..45b99584427 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,7 @@
 2006-04-26  Jason Rumney  <jasonr@gnu.org>
 
+        * w32term.c (construct_mouse_wheel): Handle negative coordinates.
+
         * w32fns.c (w32_wnd_proc) <WM_LBUTTONDOWN, WM_RBUTTONDOWN>:
         <WM_LBUTTONUP, WM_RBUTTONUP>: Call signal_user_input in the cases
         where we preempt mouse_button_timer.
diff --git a/src/w32term.c b/src/w32term.c
index f0ef42f798b..2b5c9da39b6 100644
--- a/src/w32term.c
+++ b/src/w32term.c
@@ -3131,8 +3131,10 @@ construct_mouse_wheel (result, msg, f)
   result->modifiers = (msg->dwModifiers
                        | ((delta < 0 ) ? down_modifier : up_modifier));
 
-  p.x = LOWORD (msg->msg.lParam);
-  p.y = HIWORD (msg->msg.lParam);
+  /* With multiple monitors, we can legitimately get negative
+     coordinates, so cast to short to interpret them correctly.  */
+  p.x = (short) LOWORD (msg->msg.lParam);
+  p.y = (short) HIWORD (msg->msg.lParam);
   ScreenToClient (msg->msg.hwnd, &p);
   XSETINT (result->x, p.x);
   XSETINT (result->y, p.y);