Strange Electron Webview Behavior

Noticed some strange Electron <webview> behavior while working on a proof-of-concept for the next version of Doctrine.

I have a simple page with a <webview> tag displaying a local HTML file. If the local HTML file contains a link and the user clicks on it, the default browser should open the URL instead of the <webview>.

The following code produces the expected results:

webview.addEventListener('will-navigate', (event) => {
    // Order is important or URL will open in both external browser and webview!
    shell.openExternal(event.url); // Must be first!
    webview.stop(); // Must be second!
    // event.preventDefault(); // Has no effect...
});

The following is odd about this code:

The event.preventDefault() call seems to have no effect no matter where it is placed. Would think that this call should prevent the <webview> from loading the URL but it does not.
The webview.stop() call must be after the shell.openExternal() call. This seems weird; no mention of such behavior in the documentation.

Thinking this may warrant opening a bug report...

For context, here is the output of console.log(process.versions) for my development environment:

ares : "1.10.1-DEV"
atom-shell : "1.3.0"
chrome : "52.0.2743.82"
electron : "1.3.0"
http_parser : "2.7.0"
modules : "49"
node : "6.3.0"
openssl : "1.0.2h"
uv : "1.9.1"
v8 : "5.2.361.43"
zlib : "1.2.8"