fix hover event issue for histogram

Author: Lexachoc

src/components/fx/hover.js

@@ -2283,7 +2283,8 @@ function hoverChanged(gd, evt, oldhoverdata) {
 
         if(oldPt.curveNumber !== newPt.curveNumber ||
             String(oldPt.pointNumber) !== String(newPt.pointNumber) ||
-            String(oldPt.pointNumbers) !== String(newPt.pointNumbers)
+            String(oldPt.pointNumbers) !== String(newPt.pointNumbers) ||
+            String(oldPt.binNumber) !== String(newPt.binNumber)
         ) {
             return true;
         }