Restore control’s keyboard navigation

By listening to `click` event too, but ignore it unless `evt.screenX` or `evt.screenY` equals 0. That *should* only happen when button are activated with the keyboard. 

IE is supposed to accept Enter or Space to activate links, but IE9 returns ~~completely crazy~~ incoherent `screenX/screenY` when activated with Enter, so only space works here (IE9 only).

Feedback welcome (-: