From 6f194c7811e77bb6e2e4fa69ea329dc99e2b50ef Mon Sep 17 00:00:00 2001
From: Matthew Dapena-Tretter <m@tthewwithanm.com>
Date: Thu, 1 Mar 2018 10:49:58 -0800
Subject: [PATCH] Make sure there's a single source of truth for dock hover
 state

Previously, the workspace's idea of the hovered dock and the docks'
themselves could be out of sync.
---
 src/dock.js              | 15 ++++++++++++++-
 src/workspace-element.js | 13 +++++++++----
 2 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/src/dock.js b/src/dock.js
index 3e0643c9c..a9a97b43d 100644
--- a/src/dock.js
+++ b/src/dock.js
@@ -153,7 +153,10 @@ module.exports = class Dock {
     this.state = nextState
     this.render(this.state)
 
-    const {visible} = this.state
+    const {hovered, visible} = this.state
+    if (hovered !== prevState.hovered) {
+      this.emitter.emit('did-change-hovered', hovered)
+    }
     if (visible !== prevState.visible) {
       this.emitter.emit('did-change-visible', visible)
     }
@@ -609,6 +612,16 @@ module.exports = class Dock {
     return this.paneContainer.onDidDestroyPaneItem(callback)
   }
 
+  // Extended: Invoke the given callback when the hovered state of the dock changes.
+  //
+  // * `callback` {Function} to be called when the hovered state changes.
+  //   * `hovered` {Boolean} Is the dock now hovered?
+  //
+  // Returns a {Disposable} on which `.dispose()` can be called to unsubscribe.
+  onDidChangeHovered (callback) {
+    return this.emitter.on('did-change-hovered', callback)
+  }
+
   /*
   Section: Pane Items
   */
diff --git a/src/workspace-element.js b/src/workspace-element.js
index 6d15cc14b..5531aafdf 100644
--- a/src/workspace-element.js
+++ b/src/workspace-element.js
@@ -92,7 +92,13 @@ class WorkspaceElement extends HTMLElement {
         window.removeEventListener('dragstart', this.handleDragStart)
         window.removeEventListener('dragend', this.handleDragEnd, true)
         window.removeEventListener('drop', this.handleDrop, true)
-      })
+      }),
+      ...[this.model.getLeftDock(), this.model.getRightDock(), this.model.getBottomDock()]
+        .map(dock => dock.onDidChangeHovered(hovered => {
+          if (hovered) this.hoveredDock = dock
+          else if (dock === this.hoveredDock) this.hoveredDock = null
+          this.checkCleanupDockHoverEvents()
+        }))
     )
     this.initializeContent()
     this.observeScrollbarStyle()
@@ -190,10 +196,9 @@ class WorkspaceElement extends HTMLElement {
     if (this.hoveredDock && this.hoveredDock.pointWithinHoverArea(mousePosition, true)) return
 
     const docks = [this.model.getLeftDock(), this.model.getRightDock(), this.model.getBottomDock()]
-    this.hoveredDock =
+    const nextHoveredDock =
       docks.find(dock => dock !== this.hoveredDock && dock.pointWithinHoverArea(mousePosition))
-    docks.forEach(dock => { dock.setHovered(dock === this.hoveredDock) })
-    this.checkCleanupDockHoverEvents()
+    docks.forEach(dock => { dock.setHovered(dock === nextHoveredDock) })
   }
 
   checkCleanupDockHoverEvents () {