fix: detected calling attachShadow

src/btn.ts

@@ -1,6 +1,6 @@
 
 import { loadMscore, WebMscore } from './mscore'
-import { useTimeout, windowOpen, console } from './utils'
+import { useTimeout, windowOpen, console, _Element } from './utils'
 import i18n from './i18n'
 // @ts-ignore
 import btnListCss from './btn.css'
@@ -45,6 +45,10 @@ const cloneBtn = (btn: HTMLButtonElement) => {
   return n
 }
 
+const attachShadow = (el: Element): ShadowRoot => {
+  return _Element.prototype.attachShadow.call(el, { mode: 'closed' }) as ShadowRoot
+}
+
 interface BtnOptions {
   readonly name: string;
   readonly action: BtnAction;
@@ -94,7 +98,7 @@ export class BtnList {
     } catch (err) {
       console.error(err)
     }
-    const shadow = btnParent.attachShadow({ mode: 'closed' })
+    const shadow = attachShadow(btnParent)
 
     // style the shadow DOM
     const style = document.createElement('style')

src/utils.ts

@@ -49,6 +49,7 @@ export const windowOpen: Window['open'] = (...args): Window | null => {
 }
 
 export const console: Console = getSandboxWindow()['console']
+export const _Element: typeof Element = getSandboxWindow()['Element']
 
 export const waitForDocumentLoaded = (): Promise<void> => {
   if (document.readyState !== 'complete') {