UV version: universalviewer@4.0.25

I'm submitting a: bug report => please fork one of these codesandbox examples with a repro of your issue and include a link to it below

Page area

back and forward buttons in header panel as well as image controls

Issue description

The back buttons for the first image and the forward buttons for the last image are inactive.

• in the header panel there are two on each side, one to move back or forth by one image and one to move all the way to the beginning/end of the images.
• in the image controls there is also an arrow on either side of the image that moves to the previous or next image.

The problem is that the inactivity is insufficiently conveyed: The items remain in the tabbing order so are still accessed when a user navigates by keyboard. This indicates they are acvite. The colour change for the buttons in the header panel is also relatively subtle and will not be visible to all users.

Steps to reproduce

1. open this manifest
2. navigate to any of the backward buttons and observe that they are accessible even though this is the first image and there is no previous image to move to
3. activate a screenreader and navigate to the same buttons, observe that they are announced no different from when they are active

Expected behaviour

I would expect tab order to skip inactive links/buttons/elements. Sometimes it can be useful to screenreader users to have them there so they know about certain functionality. In this case, I see no reason to do so since a user will know that where there is a next button, there will be a previous button once there is a previous item.

Possible fix

Remove the buttons from the tab order when they become inactive.

Alternatively, if it is desired that they remain in the tab order, ensure that their inactive state is in some form known to and announced by assistive technologies.

WCAG criterion

4.1.2 Name, Role, Value (Level A)

Related code example

<button class="btn imageBtn first disabled" title="First Image"><i class="uv-icon-first" aria-hidden="true"></i><span class="sr-only">First Image</span></button>