From 20bc7da2b7f2715c6b30ca2f080ebd047e841677 Mon Sep 17 00:00:00 2001
From: "REDMOND\\jspurlin" <jspurlin@microsoft.com>
Date: Tue, 17 Apr 2018 10:50:10 -0700
Subject: [PATCH 1/5] ContextualMenu: Update mousemove to only do anything if
 there is not another pending mouse enter/move/leave to improve the snappiness
 of the updates

---
 .../src/components/ContextualMenu/ContextualMenu.tsx         | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/packages/office-ui-fabric-react/src/components/ContextualMenu/ContextualMenu.tsx b/packages/office-ui-fabric-react/src/components/ContextualMenu/ContextualMenu.tsx
index 80f200115260ee..a339d6681032f1 100644
--- a/packages/office-ui-fabric-react/src/components/ContextualMenu/ContextualMenu.tsx
+++ b/packages/office-ui-fabric-react/src/components/ContextualMenu/ContextualMenu.tsx
@@ -793,7 +793,10 @@ export class ContextualMenu extends BaseComponent<IContextualMenuProps, IContext
 
     const targetElement = ev.currentTarget as HTMLElement;
 
-    if (!this._isScrollIdle || targetElement === this._targetWindow.document.activeElement as HTMLElement) {
+    if (
+      !this._isScrollIdle ||
+      this._enterTimerId !== undefined ||
+      targetElement === this._targetWindow.document.activeElement as HTMLElement) {
       return;
     }
 

From 11bb5653aabfdfd60516ee38aba06739998c73a4 Mon Sep 17 00:00:00 2001
From: "REDMOND\\jspurlin" <jspurlin@microsoft.com>
Date: Tue, 17 Apr 2018 10:55:15 -0700
Subject: [PATCH 2/5] rush change

---
 ...lMenuUpdateMouseMoveBehavior_2018-04-17-17-55.json | 11 +++++++++++
 1 file changed, 11 insertions(+)
 create mode 100644 common/changes/office-ui-fabric-react/jspurlin-ContextualMenuUpdateMouseMoveBehavior_2018-04-17-17-55.json

diff --git a/common/changes/office-ui-fabric-react/jspurlin-ContextualMenuUpdateMouseMoveBehavior_2018-04-17-17-55.json b/common/changes/office-ui-fabric-react/jspurlin-ContextualMenuUpdateMouseMoveBehavior_2018-04-17-17-55.json
new file mode 100644
index 00000000000000..84b39b0f1ff817
--- /dev/null
+++ b/common/changes/office-ui-fabric-react/jspurlin-ContextualMenuUpdateMouseMoveBehavior_2018-04-17-17-55.json
@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "packageName": "office-ui-fabric-react",
+      "comment": "ContextualMenu: Update mousemove to only do anything if there is not another pending mouse enter/move/leave to improve the snappiness of the updates",
+      "type": "patch"
+    }
+  ],
+  "packageName": "office-ui-fabric-react",
+  "email": "jspurlin@microsoft.com"
+}
\ No newline at end of file

From 0b996e563de30a6c18f3593b20ef245d617a35b8 Mon Sep 17 00:00:00 2001
From: "REDMOND\\jspurlin" <jspurlin@microsoft.com>
Date: Tue, 17 Apr 2018 11:29:57 -0700
Subject: [PATCH 3/5] change spacing

---
 .../src/components/ContextualMenu/ContextualMenu.tsx           | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/packages/office-ui-fabric-react/src/components/ContextualMenu/ContextualMenu.tsx b/packages/office-ui-fabric-react/src/components/ContextualMenu/ContextualMenu.tsx
index a339d6681032f1..41d534cdfa3dde 100644
--- a/packages/office-ui-fabric-react/src/components/ContextualMenu/ContextualMenu.tsx
+++ b/packages/office-ui-fabric-react/src/components/ContextualMenu/ContextualMenu.tsx
@@ -793,8 +793,7 @@ export class ContextualMenu extends BaseComponent<IContextualMenuProps, IContext
 
     const targetElement = ev.currentTarget as HTMLElement;
 
-    if (
-      !this._isScrollIdle ||
+    if (!this._isScrollIdle ||
       this._enterTimerId !== undefined ||
       targetElement === this._targetWindow.document.activeElement as HTMLElement) {
       return;

From 9f4883538e4feb16d359929a43480a60e4f2ea38 Mon Sep 17 00:00:00 2001
From: "REDMOND\\jspurlin" <jspurlin@microsoft.com>
Date: Tue, 17 Apr 2018 15:03:23 -0700
Subject: [PATCH 4/5] Make sure we are clearing the enterTimerId after
 executing in the settimeout

---
 .../src/components/ContextualMenu/ContextualMenu.tsx             | 1 +
 1 file changed, 1 insertion(+)

diff --git a/packages/office-ui-fabric-react/src/components/ContextualMenu/ContextualMenu.tsx b/packages/office-ui-fabric-react/src/components/ContextualMenu/ContextualMenu.tsx
index 41d534cdfa3dde..725b4e1e4c1574 100644
--- a/packages/office-ui-fabric-react/src/components/ContextualMenu/ContextualMenu.tsx
+++ b/packages/office-ui-fabric-react/src/components/ContextualMenu/ContextualMenu.tsx
@@ -860,6 +860,7 @@ export class ContextualMenu extends BaseComponent<IContextualMenuProps, IContext
         const splitButtonContainer = this._splitButtonContainers.get(item.key);
         this._onItemSubMenuExpand(item,
           ((item.split && splitButtonContainer) ? splitButtonContainer : targetElement) as HTMLElement);
+        this._enterTimerId = undefined;
       }, this._navigationIdleDelay);
     } else {
       this._enterTimerId = this._async.setTimeout(() => {

From 8bb49e3ddb09245548a3aedf0372f50bd3ae983a Mon Sep 17 00:00:00 2001
From: "REDMOND\\jspurlin" <jspurlin@microsoft.com>
Date: Wed, 18 Apr 2018 05:34:03 -0700
Subject: [PATCH 5/5] fix missing line to set enterTimerId back to undefined if
 the item does not have a submenu

---
 .../src/components/ContextualMenu/ContextualMenu.tsx             | 1 +
 1 file changed, 1 insertion(+)

diff --git a/packages/office-ui-fabric-react/src/components/ContextualMenu/ContextualMenu.tsx b/packages/office-ui-fabric-react/src/components/ContextualMenu/ContextualMenu.tsx
index 725b4e1e4c1574..bf64647c86c86c 100644
--- a/packages/office-ui-fabric-react/src/components/ContextualMenu/ContextualMenu.tsx
+++ b/packages/office-ui-fabric-react/src/components/ContextualMenu/ContextualMenu.tsx
@@ -866,6 +866,7 @@ export class ContextualMenu extends BaseComponent<IContextualMenuProps, IContext
       this._enterTimerId = this._async.setTimeout(() => {
         this._onSubMenuDismiss(ev);
         targetElement.focus();
+        this._enterTimerId = undefined;
       }, timeoutDuration);
     }
   }