diff --git a/src/btn.ts b/src/btn.ts
index 47b543f..c0b69e3 100644
--- a/src/btn.ts
+++ b/src/btn.ts
@@ -148,7 +148,7 @@ export class BtnList {
 
       case BtnListMode.ExtWindow: {
         const div = this._commit()
-        const w = await windowOpenAsync('', undefined, 'resizable,width=230,height=270')
+        const w = await windowOpenAsync(undefined, '', undefined, 'resizable,width=230,height=270')
         // eslint-disable-next-line no-unused-expressions
         w?.document.body.append(div)
         window.addEventListener('unload', () => w?.close())
@@ -174,12 +174,6 @@ export namespace BtnAction {
     else return url
   }
 
-  export const openUrl = (url: UrlInput): BtnAction => {
-    return process(async (): Promise<any> => {
-      return windowOpenAsync(await normalizeUrlInput(url))
-    })
-  }
-
   export const download = (url: UrlInput, fallback?: () => Promisable<void>, timeout?: number): BtnAction => {
     return process(async (): Promise<void> => {
       const _url = await normalizeUrlInput(url)
@@ -195,7 +189,7 @@ export namespace BtnAction {
       btn.onclick = null
       setText(i18n('PROCESSING')())
 
-      const w = await windowOpenAsync('') as Window
+      const w = await windowOpenAsync(btn, '') as Window
       const txt = document.createTextNode(i18n('PROCESSING')())
       w.document.body.append(txt)
 
diff --git a/src/utils.ts b/src/utils.ts
index fbdbee2..02e339b 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -47,11 +47,10 @@ export const useTimeout = async <T> (promise: T | Promise<T>, ms: number): Promi
   })
 }
 
-export const getSandboxWindowAsync = async (): Promise<Window> => {
+export const getSandboxWindowAsync = async (targetEl = document.documentElement): Promise<Window> => {
   if (typeof document === 'undefined') return {} as any as Window
 
   return new Promise((resolve) => {
-    const targetEl = document.documentElement
     const eventName = 'onmousemove'
     const id = Math.random().toString()
 
@@ -76,8 +75,8 @@ export const getUnsafeWindow = (): Window => {
 
 export const console: Console = (window || global).console // Object.is(window.console, unsafeWindow.console) == false
 
-export const windowOpenAsync = (...args: Parameters<Window['open']>): Promise<Window | null> => {
-  return getSandboxWindowAsync().then(w => w.open(...args))
+export const windowOpenAsync = (targetEl = document.documentElement, ...args: Parameters<Window['open']>): Promise<Window | null> => {
+  return getSandboxWindowAsync(targetEl).then(w => w.open(...args))
 }
 
 export const attachShadow = (el: Element): ShadowRoot => {