Commit fix for an off-by-two error on standards complaint HTML pages in IE, and

add an HTML example that can be used as an acceptance test. (Closes #863) 
Thanks pierre for the research and report!


git-svn-id: http://svn.openlayers.org/trunk/openlayers@4098 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Events.js

@@ -656,9 +656,11 @@ OpenLayers.Events = OpenLayers.Class({
         }
         return new OpenLayers.Pixel(
             (evt.clientX + (document.documentElement.scrollLeft
-                         || document.body.scrollLeft)) - this.element.offsets[0], 
+                         || document.body.scrollLeft)) - this.element.offsets[0]
+                         - (document.documentElement.clientLeft || 0), 
             (evt.clientY + (document.documentElement.scrollTop
-                         || document.body.scrollTop)) - this.element.offsets[1] 
+                         || document.body.scrollTop)) - this.element.offsets[1]
+                         - (document.documentElement.clientTop || 0)
         ); 
     },