[SOL-2077] Prevent 'Change Background' button from forcing form submission

[haikuginger]

As part of #88, we inadvertently removed a PreventDefaults call from the event handler for the "Change Background" button. Since some browsers default the type of <button> elements to submit, this resulted in the form being submitted synchronously, resulting in a page reload, and preventing the updated image URI from being saved. This change explicitly sets that button's type to "button", which has no default submission behavior.

JIRA tickets: Fixes SOL-2077

Testing instructions:

1. In a devstack running the master version of DnDv2, create a problem.
2. Attempt to set the background image of that problem to a different URL; set the value, and click the "Change Background" button.
3. Observe that the form is immediately submitted and the page refreshed.
4. Observe that your new image is not used.
5. Install this branch.
6. Again attempt to set the background image; set the value, click the "Change Background" button, click the "Continue" button, and click "Save".
7. Observe that the configuration dialog is not closed when you click "Change Background".
8. Observe that after clicking Save, your image choice is used for the DnDv2 problem.

Reviewers

• @pomegranited
• TNL: @cahrens and/or @staubina
• a11y: @edx/edx-accessibility
• Product: @sstack22

[openedx-webhooks]

Thanks for the pull request, @haikuginger! It looks like you're a member of a company that does contract work for edX. If you're doing this work as part of a paid contract with edX, you should talk to edX about who will review this pull request. If this work is not part of a paid contract with edX, then you should ensure that there is an OSPR issue to track this work in JIRA, so that we don't lose track of your pull request.

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[pomegranited]

👍

• I tested this on my devstack, using the PR's instructions.
• I read through the code.
• Includes documentation Bugfix, no documentation required.

[openedx-webhooks]

Thanks for the pull request, @haikuginger! I've created OSPR-1458 to keep track of it in JIRA. JIRA is a place for product owners to prioritize feature reviews by the engineering development teams.

Feel free to add as much of the following information to the ticket:

• supporting documentation
• edx-code email threads
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[haikuginger]

Pinging the relevant teams for review:

• TNL: @cahrens and/or @staubina
• a11y: @edx/edx-accessibility
• Product: @sstack22

Note that we're having some issues with our sandbox infrastructure at present, so we don't have one yet, but will spawn one ASAP.

[cahrens]

👍

[staubina]

👍

[haikuginger]

Per @antoviaque, I'm adding a version bump to 2.0.10 in this PR so we can get this fix into tomorrow's OpenEdX release. I am planning on merging ASAP once Travis goes green so I can open an edx-platform version bump PR, so if @pomegranited, @cahrens, and/or @staubina want to give the version bump notes a once-over for any glaring issues prior to that, that'd be great.

[pomegranited]

@haikuginger I think we need a 👍 from Product (@sstack22) before merge? @antoviaque can you confirm?

But your notes look fine. Thanks for doing the version bump!

[sstack22]

👍 !