Yeah, this is something I'm trying to figure out for a long time. First of all, a button saying 'Send me an email' is logically a "new window action" as it will open a mail client. For external apps _blank will be ignored. For those who set Gmail (or other webmail) to handle mailto: links in the browser without _blank it will be loaded in same tab/window replacing the site, which is not a logical and expected behaviour. With Gmail it looks really bad. Clicking mailto: link opens in current window/tab a blank page with Gmail's 'compose' overlay div and after sending the message this overlay is automatically closed leaving you in front of a blank page. Awkward. But wait, that's not all! When you hit browser's back button you see a 'compose' overlay again instead of going back to the site. What most users will do in this case? Close the tab/window. This is not a user-friendly behavior. I think that 'Contact me' link is not an internal/external LINK to be followed, it's an external ACTION, which by default will be handled in separate window (external application or webmail in external window) or it can handle an overlay with contact form..
the alt must replicate the text rendered in the graphic
It makes no sense for me, really. Looks like just stupid following some strict rule, not thinking about the end user but about getting 'WCAG Passed' badge. First of all, the button is not a graphic, it's a PLAIN TEXT link 'Contact me', it is a text and it is accessible. The alt attribute, as I understand, gives alternative readers some extra information - explanation, instruction etc. Replicating 'Contact me' text in alt attribute makes no sense because it doesn't help and it's actually redundant, because the link text is accessible itself. Alt text here is kinda optional instruction for alternative reader. What am I missing?
have you tried putting your theme through the theme accessibility audit yourself?
Not yet, until now I developed themes only for personal projects and clients. Right now working on my first theme to be released in public and will definitely try this out. Thanks!