use 2d items for hotbar

src/js/net/minecraft/util/Keyboard.js

@@ -4,10 +4,12 @@ window.Keyboard = class {
 
     static create() {
         window.addEventListener('keydown', function (event) {
+            event.preventDefault();
             Keyboard.state[event.code] = true;
             //console.log("Key " + event.code + " down");
         });
         window.addEventListener('keyup', function (event) {
+            event.preventDefault();
             delete Keyboard.state[event.code];
             //console.log("Key " + event.code + " up");
         });