I tried the plugin out with a few other plugins enabled. One was Shortcodes Ultimate.
Shortcodes Ultimate creates a number of shortcodes including "buttons" (really links styled as buttons). Here's an example:
[su_button url="https://content-accessibility.local" target="self" style="default" background="#2D89EF" color="#FFFFFF" size="3" wide="no" center="no" radius="auto" icon="" icon_color="#FFFFFF" text_shadow="none" desc="" onclick="" rel="" title="" id="" class=""]Button text[/su_button]
Here's the rendered code:
<a href="https://content-accessibility.local" class="su-button su-button-style-default" style="color:#FFFFFF;background-color:#2D89EF;border-color:#246ebf;border-radius:5px;-moz-border-radius:5px;-webkit-border-radius:5px" target="_self"><span style="color:#FFFFFF;padding:0px 16px;font-size:13px;line-height:26px;border-color:#6cacf4;border-radius:5px;-moz-border-radius:5px;-webkit-border-radius:5px;text-shadow:none;-moz-text-shadow:none;-webkit-text-shadow:none"> Button text</span></a>
I noticed that Content Author Accessibility Preview marks this as a "link opens new window" even though the target attribute is set to self. When you add a "button" in this way, there's a dropdown, with the options Open in new tab or Open in same tab, so you can't avoid adding the target attribute altogether. You could remove it from the shortcode afterwards, but most users won't know how to do that.
Therefore, in content-author-accessibility-preview.php
line 171, would it be better to have 'selector' => $container . ' a[target=_blank]',
rather than 'selector' => $container . ' a[target]',
?