Only fire ButtonView on mouseup if in MenuView.
Only fire ButtonView on mouseup if in MenuView.

* Otherwise look for a click event
* Must fire on mouseup in menu to allow down-drag-up selection
* Must not fire on mouseup outside, as this can lead to unexpected activation of
  buttons.

Hokua/overture,adityab/overture,linagora/overture,linagora/overture,fastmail/overture