Can you wrap your summary at 72 characters, but ideally 52 characters. Commit summaries needn't end in a period.

You can have your testing done render a list using:

Tested behaviour in Chrome, Safari in Firefox:

1. Something
2. Another thing
3. Yet another thing.

The issue was originally filed against reviewboard 2.5.x.
Can you apply your patch on that branch, test, and re-post?
Note:
To get Reviewboard 2.5.x to work, you will need a new virtual environment with Review Board at release-2.5.x and Djblets at release-0.9.x. You do not need another source checkout of RB or Djblets -- another virtualenv will suffice.

Could you add a screen shot of your work?

Can you wrap your description at 72 characters?

How about:
"The confirmation dialog will allow the user to cancel the creation of the review request."

We may want to add more context to the message here, something like:

You are creating a new review request from a commit that has already been published. Are you sure you want to continue?

This string needs to be marked for translation with gettext().

This string needs to be marked for translation with gettext().
Missing trailing comma.

This string needs to be marked for translation with gettext().

Unfortunately, we can't use ES6 arrow functions here. We'll have to do _.bind(this._createNewReviewRequest, this) instead.
This is because we have customers on older versions of IE (I know :( ). We do allow arrow functions in .es6.js files, which are transpiled with Babel to ES5 that can run on all these browsers.
However, since this patch will be backported to 2.5.x, we don't be able to use that. Sorry.

Ideally this long message would be in the body of the dialog instead of the title

Instead of doing this, lets define a subclass that will display this content. We can refactor it out into a generic class at a later date.
If you wrap the contents of the file in an IIFE, we can have it local to the file.

Can you add body and title here?
The title should be something like "Are you sure?" or "Create review request?"

This should really be in the default impl of render above. Also, doing _.result twice may result in us calling an expensive function twice. Lets do:

var body;

/* snip */

body = _.result(this, 'body');

if (body !== undefined) {
    this.$el.append($('<p>').text(body));
}

Title case: Create Review Request?

While you're here, would you mind updating the doc comment to take the following format:

/**
 * Initialze the view.
 * 
 * Args:
 *     options (object):
 *         Options for the view.
 *
 * Option Args:
 *     body (string or function, optional):
 *         <Description of body.>
 *         
 *     title (string, optional):
 *         <Description of title.>
 *
 *     buttons (object, optional):
 *         <Description of buttons.>
 */

Need a var body statement at the top of the function.

if (body) {

One more request to add to the design of this: can we include the commit summary in the text of the dialog, so people can verify that they clicked on the one they intended to?

Instead of duplicating this I would just do

See the :js:class:`class-level documentation <RB.DialogView>` for the keys that this object accepts.

Just a few tiny nits left.

Let's sort these alphabetically.

Please put a blank line between these two.

Instead of <b>, let's just use <span> and then put font-weight: bold in the CSS.

Because this is an ES5 file, no trailing comma on the last item in an object.

Because this is an ES5 file, no trailing comma on the last item in an object.

A few things here. Wrapping everything in gettext wont work. gettext() requires the value to a be a string literal, otherwise the code that looks for things to translate won't be able to parse this.
Also, we want to avoid using inline styles when possible. This should be included in the rules for .summary in the LESS file.
Instead, lets use a template on the class:

{
    _dialogTemplate: _.template([
        '<p><%- prefixText %></p>',
        '<p class="summary">',
        ' <%- commitID %>: <%- summary %>',
        '</p>',
        '<p><%- suffixText %></p>',
    ].join('')),
}


For more details on _.template, check out the docs.
Then we can use it like so:

var dialogView = new RB.DialogView({
    title: gettext('Create Review Request?'),
    body: this._dialogTemplate({
        prefixText: gettext('You are creating a new review request from the following published commit:'),
        suffixText: gettext('Are you sure you want to continue?'),
    }), 
    buttons: [ /* ... */ ]
});


This allows us to only mark the string literals for translation. Additionally, lets use <p> tags for content separation instead of <br>, as that is what they exist for.

Two minor nits, but otherwise looks good to me!

While you're here, can you change this to /**? Otherwise it doesn't get picked up by the documentation generation tool

And this?

Tiny nit: summaries don't need a period.

Also your summary should be in the imperitive mood as if it were an order. If you substitute your sumamry into the following sentence it should make sense:

This patch will <summary>


So Add confirmation dialog ... would work or similar.

This is only used once, so instead of defining a variable, you could do it inline:

body: this._dialogBodyTemplate({
    prefixText: gettext('...'),
    commitID: commitID,
    summary: this.model.get('summary'),
    suffixText: ...
}),

In ES5, all variables need to be defined at the top of the function. So:

var commitID = this.model.get('id'),
    dialogView;

if (commitID.length > 7) {
    commitID = commitID.slice(0, 7);
}

dialogView = new RB.DialogView({
    ...

Wrap to 79 columns.

Ship It!

Ship It!