Function e_button

external/.scrollLibs.js:2051–2066

(e)

    return e.target || e.srcElement
  }
  function e_button(e) {
    var b = e.which
    if (b == null) {
      if (e.button & 1) {
        b = 1
      } else if (e.button & 2) {
        b = 3
      } else if (e.button & 4) {
        b = 2
      }
    }
    if (mac && e.ctrlKey && b == 1) {
      b = 3
    }
    return b
  }

  // Detect drag-and-drop
  var dragAndDrop = (function () {