Windows锁定获取访问权限时使用SendKeys

I have a .NET Winform with a WebBrowser control that logs in to a website using username and password. The "submit" button is disabled until something is entered into the password textbox, so I can't use txt.SetAttribute() because it doesn't seem to enable the submit button. Using SendKeys.Send(password) works fine, and the submit button is enabled. I have a .NET Winform with a WebBrowser control