improve page unloading

src/js/Start.js

@@ -48,5 +48,10 @@ class Start {
     }
 }
 
-// Launch game
+// Listen on history back
-new Start().launch("canvas-container");
+window.addEventListener('pageshow', function (event) {
+    // Launch game
+    if (!window.app || !window.app.running) {
+        new Start().launch("canvas-container");
+    }
+});

src/js/net/minecraft/client/Minecraft.js

@@ -127,8 +127,6 @@ export default class Minecraft {
             if (this.running) {
                 this.requestNextFrame();
                 this.onLoop();
-            } else {
-                this.window.close();
             }
         });
     }
@@ -372,10 +370,14 @@ export default class Minecraft {
     }
 
     stop() {
+        if (this.currentScreen !== null) {
+            this.currentScreen.onClose();
+        }
         this.running = false;
         this.worldRenderer.reset();
         this.itemRenderer.reset();
         this.screenRenderer.reset();
+        this.window.close();
     }
 
     getThreeTexture(id) {

src/js/net/minecraft/client/render/gui/ScreenRenderer.js

@@ -47,7 +47,7 @@ export default class ScreenRenderer {
     }
 
     reset() {
-        this.stack2d.clearRect(0, 0, this.window.width, this.window.height);
+        this.stack2d.clearRect(0, 0, this.window.canvas2d.width, this.window.canvas2d.height);
     }
 
 }