Help understanding ui_defaults

Development
1

I’ve just inherited a Collabora codebase and trying to understand how the ui_defaults input works.

I’d ideally like to start the PowerPoint/ Presentations app in compact mode but I’m unable to get the following to work.

<form id="office_form" name="office_form" target="office_frame" action="@Model.ActionUri" method="post" style="display: none;">
    <input name="access_token" value="@Model.AccessToken" type="hidden" />
    <input name="access_token_ttl" value="@Model.AccessTokenTtl" type="hidden" />
    <input name="ui_defaults" value="UIMode=compact;" type="hidden" />
</form>

@section scripts
{
    <script type="text/javascript">
        document.getElementById('office_form').submit();

This was based off the following help topic - Making sure you're not a bot!

Any help would be very much appreciated