Fix #4077

dist/preview release/gui/babylon.gui.d.ts

@@ -58,6 +58,10 @@ declare module BABYLON.GUI {
         private _checkUpdate(camera);
         private _render();
         private _doPicking(x, y, type, pointerId, buttonIndex);
+        _cleanControlAfterRemovalFromList(list: {
+            [pointerId: number]: Control;
+        }, control: Control): void;
+        _cleanControlAfterRemoval(control: Control): void;
         attach(): void;
         attachToMesh(mesh: AbstractMesh, supportPointerMove?: boolean): void;
         moveFocusToControl(control: IFocusableControl): void;

dist/preview release/gui/babylon.gui.js

@@ -391,6 +391,21 @@ var BABYLON;
                 }
                 this._manageFocus();
             };
+            AdvancedDynamicTexture.prototype._cleanControlAfterRemovalFromList = function (list, control) {
+                for (var pointerId in list) {
+                    if (!list.hasOwnProperty(pointerId)) {
+                        continue;
+                    }
+                    var lastControlOver = list[pointerId];
+                    if (lastControlOver === control) {
+                        delete list[pointerId];
+                    }
+                }
+            };
+            AdvancedDynamicTexture.prototype._cleanControlAfterRemoval = function (control) {
+                this._cleanControlAfterRemovalFromList(this._lastControlDown, control);
+                this._cleanControlAfterRemovalFromList(this._lastControlOver, control);
+            };
             AdvancedDynamicTexture.prototype.attach = function () {
                 var _this = this;
                 var scene = this.getScene();
@@ -2083,6 +2098,9 @@ var BABYLON;
                     control.parent = null;
                 }
                 control.linkWithMesh(null);
+                if (this._host) {
+                    this._host._cleanControlAfterRemoval(control);
+                }
                 this._markAsDirty();
                 return this;
             };

dist/preview release/gui/babylon.gui.module.d.ts

@@ -63,6 +63,10 @@ declare module BABYLON.GUI {
         private _checkUpdate(camera);
         private _render();
         private _doPicking(x, y, type, pointerId, buttonIndex);
+        _cleanControlAfterRemovalFromList(list: {
+            [pointerId: number]: Control;
+        }, control: Control): void;
+        _cleanControlAfterRemoval(control: Control): void;
         attach(): void;
         attachToMesh(mesh: AbstractMesh, supportPointerMove?: boolean): void;
         moveFocusToControl(control: IFocusableControl): void;

gui/src/advancedDynamicTexture.ts

@@ -419,6 +419,24 @@ module BABYLON.GUI {
             this._manageFocus();
         }
 
+        public _cleanControlAfterRemovalFromList(list: {[pointerId:number]:Control}, control:Control) {
+            for (var pointerId in list) {
+                if (!list.hasOwnProperty(pointerId)) {
+                    continue;
+                }
+
+                var lastControlOver = list[pointerId];
+                if (lastControlOver === control) {
+                    delete list[pointerId];
+                }
+            }
+        }
+
+        public _cleanControlAfterRemoval(control: Control) {
+            this._cleanControlAfterRemovalFromList(this._lastControlDown, control);
+            this._cleanControlAfterRemovalFromList(this._lastControlOver, control);
+        }
+
         public attach(): void {
             var scene = this.getScene();
             if (!scene) {

gui/src/controls/container.ts

@@ -120,6 +120,10 @@ module BABYLON.GUI {
 
             control.linkWithMesh(null);
 
+            if (this._host) {
+                this._host._cleanControlAfterRemoval(control);
+            }
+
             this._markAsDirty();
             return this;
         }

sandbox/index.html

@@ -22,6 +22,7 @@
     <meta name="msapplication-TileImage" content="http://www.babylonjs.com/img/favicon/ms-icon-144x144.png">
     <meta name="msapplication-config" content="http://www.babylonjs.com/img/favicon/browserconfig.xml">
     <meta name="theme-color" content="#ffffff">
+    <meta name="keywords" content="3D, Babylon.js, webgl, gltf, viewer">
 
     <link href="index.css" rel="stylesheet" />
     <script src="https://code.jquery.com/pep/0.4.2/pep.min.js"></script>
@@ -49,7 +50,7 @@
         <img id="helpArrow" src="./Assets/FlecheTuto.png" />
     </div>
     <div id="help02" class="help2">
-        <span class="helpText">Or directly drag'n'drop your files in the browser</span>
+        <span class="helpText">Or directly drag'n'drop your files (in .babylon, .gltf, .glb, .obj format) in the browser</span>
     </div>
     <div id="footer" class="footer">
         <div class="footerLeft">