only insert menu options on click

[trungpham]

it seems that the latest version of the code creates the menu options and insert them into the DOM before the user clicks on the trigger.

This is a waste of DOM nodes if there is a lot of menu triggers on the page.

Should only create the DOM when the user clicks on the menu trigger.

[knomedia]

i believe this was necessary for a11y. can you confirm @mzabriskie?

[dmitry]

@mzabriskie ping