Screenreader and series buttons

[vanch3d]

The buttons to remove sections of the charts are just announced as checkboxes: there is no indication of what the checkboxes do. High priority.
(This is probably an issue for all users, but particularly screenreader users.)

[vanch3d]

Works with NVDA on Firefox and Chrome: reads both button text and title: “Group 2 check box checked Show or hide key words from this group”.
On IE, NVDA reads twice the title, but not the text.
On Chrome with ChromeVox, only title are read, not button’s text: “Show or hide key words from this group check box checked”
ARIA tags are correct.

Workaround: changed title of each button to include name of group “'Show or hide key words from Group XXXX”