begin context menu

package/index.html

@@ -175,6 +175,7 @@ const wasm_app_imports = {
 
     addEventListener("resize", (event) => { wake_up(); });
     addEventListener("keydown", (event) => {
+        event.preventDefault();
         wasm_exports["wasm_key_down"](mem.write_string_to_cglobal("wasm_temp_buff1", event.key), event.ctrlKey, event.shiftKey, event.altKey, event.metaKey);
         wake_up();
     });