Make content attribute text selected

I have a cool tip for working with some data attributes, as shown here: http://www.frequency-decoder.com/demo/css-tooltips/

But the problem is that the text inside the tooltip is not available, even after adding the property:

cursor: text;

Any idea how to make this tooltip available?

thank

UPDATE: This also does not help:

-webkit-touch-callout: all;
-webkit-user-select: all;
-khtml-user-select: all;
-moz-user-select: all;
-ms-user-select: all;
user-select: all;

Values: none | text | switching | element | elements | all | inherit

Ref:

How to disable text selection highlighting using CSS?

http://www.w3.org/TR/2000/WD-css3-userint-20000216#user-select