Still happens with whatever version of Horizon we’ve got deployed at the moment. (I’m not sure if this is actually a Horizon feature? I couldn’t find any trace of “remember me” in the upstream tarballs for 18.3.2 or 17.0.0. Is it an in-house thing?)

The HTML looks like this (with whitespace cleaned up):

<div class="form-group ">
  <div class="">
    <div class="themable-checkbox">
      <input type="checkbox" name="rememberme" id="id_rememberme">
      <label for="id_rememberme">
        <span class="control-label">Remember me</span>
        <span class="help-icon" data-toggle="tooltip" data-placement="top" title="Stay logged in for up to 7 days of inactivity.">
          <span class="fa fa-question-circle"></span>
        </span>
      </label>
    </div>
  </div>
</div>

And the styles include (again, cleaned up):

.themable-checkbox input[type=checkbox] {
  display: none;
}

The display: none causes the checkbox to be unavailable for tabbing; the Firefox accessibility dev tools also flag this up as a warning:

⚠ Clickable elements must be focusable and should have interactive semantics.

I couldn’t find a good way to solve this; adding tabindex=0 on the <label> makes it tabbable, but pressing Space or Enter doesn’t toggle the checkbox, and presumably this wouldn’t fix the accessibility issue either.

It’s probably best to not use this themable-checkbox class, whatever framework it’s from, and use a browser checkbox instead.

Is it an in-house thing?

The "remember feature" is an in-house thing, but the checkbox styling in itself doesn't seem to be.