Here is what I have done: http://jsfiddle.net/cYHae/4/
Here is the code:
// <select> element displays its options on mousedown, not click.
showDropdown = function (element) {
var event;
event = document.createEvent('MouseEvents');
event.initMouseEvent('mousedown', true, true, window, 0, event.screenX, event.screenY, event.clientX, event.clientY,event.ctrlKey, event.altKey, event.shiftKey, event.metaKey, 0, null);
element.dispatchEvent(event);
};
// This isn't magic.
window.runThis = function () {
var dropdown = document.getElementById('dropdown');
showDropdown(dropdown);
};
It just does not work in Firefox. Why?