gmail-fluidapp-userscript.js

// use for patterns:
//   *gmail.com*
//   *mail.google.com*
//   *google.com*mail*

window.fluid.dockBadge = '';
setTimeout(updateDockBadge, 3000);
setInterval(updateDockBadge, 15000);

function updateDockBadge() {
  var inboxLink = document.querySelector('a[title^="Inbox"]');
	var regex = /\s*Inbox\s*\((\d+)\)[^\d]*/;
	var res = inboxLink.title.match(regex);

	if (res && res.length > 1) {
		var newBadge = res[1];
		window.fluid.dockBadge = newBadge;
	} else {
		regex = /^Inbox$/;
		if(regex.test(inboxLink.title)){
			window.fluid.dockBadge = '';
		}
	}
}