Add support for horizontal scroll wheel. (Bjorn Winckler)
diff --git a/src/misc2.c b/src/misc2.c
index 98f2991..6b9ffe1 100644
--- a/src/misc2.c
+++ b/src/misc2.c
@@ -2362,8 +2362,12 @@
     {K_RIGHTMOUSE,	(char_u *)"RightMouse"},
     {K_RIGHTDRAG,	(char_u *)"RightDrag"},
     {K_RIGHTRELEASE,	(char_u *)"RightRelease"},
-    {K_MOUSEDOWN,	(char_u *)"MouseDown"},
-    {K_MOUSEUP,		(char_u *)"MouseUp"},
+    {K_MOUSEDOWN,	(char_u *)"ScrollWheelUp"},
+    {K_MOUSEUP,		(char_u *)"ScrollWheelDown"},
+    {K_MOUSELEFT,	(char_u *)"ScrollWheelRight"},
+    {K_MOUSERIGHT,	(char_u *)"ScrollWheelLeft"},
+    {K_MOUSEDOWN,	(char_u *)"MouseDown"}, /* OBSOLETE: Use	  */
+    {K_MOUSEUP,		(char_u *)"MouseUp"},	/* ScrollWheelXXX instead */
     {K_X1MOUSE,		(char_u *)"X1Mouse"},
     {K_X1DRAG,		(char_u *)"X1Drag"},
     {K_X1RELEASE,		(char_u *)"X1Release"},