When a page has no discussion yet, this status is indicated by the red colour of the “Discussion” link in the tab at the top, but not by other means. This is an accessibility blocker, because information conveyed by colour must also be indicated in text or markup: Priority 1 in WCAG 1.0 (http://www.w3.org/TR/WCAG10/wai-pageauth.html#tech-color-convey), Level A in WCAG 2.0 (http://www.w3.org/TR/WCAG20/#visual-audio-contrast-without-color).
This could be fixed simply by appending “(page does not exist)” to the title attribute as is done for red links in the body of a page, or by changing the title from “Discussion about the content page” to “Start discussion about the content page”.
|Discussion tab in Vector for talk page (tooltip does not indicate inexistent state)|
|Inline link in Vector to an inexistent page (tooltip indicating page does not exist)|