From 39cdaeb34dfe58cfd4a31b1f9e340bc906a918f1 Mon Sep 17 00:00:00 2001
From: Jermolene <jeremy@jermolene.com>
Date: Fri, 17 Mar 2017 14:54:30 +0000
Subject: [PATCH] Fix problem with tracking dragenter/leave events in Firefox

Fixes #686 (hopefully!)
---
 core/modules/widgets/dropzone.js | 37 ++++++++++++++++----------------
 1 file changed, 19 insertions(+), 18 deletions(-)

diff --git a/core/modules/widgets/dropzone.js b/core/modules/widgets/dropzone.js
index 4ac8e78f4..48c1b0368 100644
--- a/core/modules/widgets/dropzone.js
+++ b/core/modules/widgets/dropzone.js
@@ -50,32 +50,35 @@ DropZoneWidget.prototype.render = function(parent,nextSibling) {
 	parent.insertBefore(domNode,nextSibling);
 	this.renderChildren(domNode,null);
 	this.domNodes.push(domNode);
+	// Stack of outstanding enter/leave events
+	this.currentlyEntered = [];
 };
 
-DropZoneWidget.prototype.enterDrag = function() {
-	// Check for this window being the source of the drag
-	if($tw.dragInProgress) {
-		return false;
+DropZoneWidget.prototype.enterDrag = function(event) {
+	if(this.currentlyEntered.indexOf(event.target) === -1) {
+		this.currentlyEntered.push(event.target);
 	}
-	// We count enter/leave events
-	this.dragEnterCount = (this.dragEnterCount || 0) + 1;
 	// If we're entering for the first time we need to apply highlighting
-	if(this.dragEnterCount === 1) {
-		$tw.utils.addClass(this.domNodes[0],"tc-dragover");
-	}
+	$tw.utils.addClass(this.domNodes[0],"tc-dragover");
 };
 
-DropZoneWidget.prototype.leaveDrag = function() {
-	// Reduce the enter count
-	this.dragEnterCount = (this.dragEnterCount || 0) - 1;
+DropZoneWidget.prototype.leaveDrag = function(event) {
+	var pos = this.currentlyEntered.indexOf(event.target);
+	if(pos !== -1) {
+		this.currentlyEntered.splice(pos,1);
+	}
 	// Remove highlighting if we're leaving externally
-	if(this.dragEnterCount <= 0) {
+	if(this.currentlyEntered.length === 0) {
 		$tw.utils.removeClass(this.domNodes[0],"tc-dragover");
 	}
 };
 
 DropZoneWidget.prototype.handleDragEnterEvent  = function(event) {
-	this.enterDrag();
+	// Check for this window being the source of the drag
+	if($tw.dragInProgress) {
+		return false;
+	}
+	this.enterDrag(event);
 	// Tell the browser that we're ready to handle the drop
 	event.preventDefault();
 	// Tell the browser not to ripple the drag up to any parent drop handlers
@@ -97,11 +100,11 @@ DropZoneWidget.prototype.handleDragOverEvent  = function(event) {
 };
 
 DropZoneWidget.prototype.handleDragLeaveEvent  = function(event) {
-	this.leaveDrag();
+	this.leaveDrag(event);
 };
 
 DropZoneWidget.prototype.handleDropEvent  = function(event) {
-	this.leaveDrag();
+	this.leaveDrag(event);
 	// Check for being over a TEXTAREA or INPUT
 	if(["TEXTAREA","INPUT"].indexOf(event.target.tagName) !== -1) {
 		return false;
@@ -112,8 +115,6 @@ DropZoneWidget.prototype.handleDropEvent  = function(event) {
 	}
 	var self = this,
 		dataTransfer = event.dataTransfer;
-	// Reset the enter count
-	this.dragEnterCount = 0;
 	// Remove highlighting
 	$tw.utils.removeClass(this.domNodes[0],"tc-dragover");
 	// Import any files in the drop