Section 5.2.1 says that “If any modal dialog box, such as those opened by on window.onbeforeunload or window.alert, is opened at any point in the page load, a response MUST be sent.”

Because we need to do this as a precondition for almost all commands I suggest we make it a definition that each command's algorithm can refer to.

The language also need to be cleaned up, and I suggest something along the lines of:

- Define a global state that signifies whether an alert dialogue is open.
- Create a definition of how what steps to take when the previous state is true, including the steps to populate the response with the correct status.
- Add this as a precondition to all commands where we need to check for this.

I imagine we can use a language like this for the POST /session/{session_id}/url command:

“All <a>alert dialogs</a> created during <code><a>beforeunload</a></code> are subject to <a>unexpected alert handling</a>.”

And a definition of alert dialogs:

“<code><a>Window.alert</a></code>, <code><a>Window.confirm</a></code>, and <code><a>Window.prompt</a></code> are considered <dfn>alert dialogs</dfn>.”

Then some text on how to handle the dialogs:

“<a>Alert dialogs</a> block document script execution and WebDriver behaves the same way.  When <a>alert dialogs</a> are created commands are free to choose if they should affect their response.  The following steps may be run when a command requests <dfn>unexpected alert handling</dfn> on <var>request</var>:

<ul>
 <li>If the <a>current alert</a> is defined:
  <ul>
   <li>Let <var>response</var>'s status be <a>unexpected alert open</a>.
   <li>Return response and abort the remaining steps.
  </ul>
 <li>Otherwise, return.
</ul>”

Then the definition of “current alert”:

“The remote end must keep a global state <dfn>current alert</dfn> that is an initially left undefined <a>alert</a>.  When any of the <a>alert dialogs</a> appear, this state must be updated with a reference to that alert.”

And then we need a definition of an “alert” struct which we can use in the algorithm for interacting with the alert.