This is a UserScript that fixes the most irritating thing about uWaterloo LEARN - the pointless, annoying alerts that your session is about to be logged out for the 50th time.

Waterloo LEARN Login.user.js

// ==UserScript==
// @name        uWaterloo Learn Login
// @namespace   uberi
// @description Keep the user logged into LEARN while the tab is open
// @include     https://learn.uwaterloo.ca/*
// @match       https://learn.uwaterloo.ca/*
// @version     1.0
// @run-at      document-start
// ==/UserScript==

/*
HOW TO INSTALL (GOOGLE CHROME):
 
1. Download the script below to a file named `BLABLABLA.user.js`. Or press the "Download Gist" button on the left and extract it or whatever.
2. Open the extensions page (Chrome Menu > Tools > Extensions).
3. Drag and drop the script file onto the extensions page.
4. Enjoy life a little bit more.
 
HOW TO INSTALL (FIREFOX):
 
Figure it out yourself, I'm already behind on my assignments.
*/

var inject_code = [
    "var old_alert = window.alert;",
    "window.alert = function(message) {",
    "    if (typeof message !== \"string\" || !/Your session has been inactive for some time/.test(message))",
    "        old_alert(message);",
    "}"
].join("\n");

// inject the stuff into the thing
var script_tag = document.createElement("script");
script_tag.type = "text/javascript";
script_tag.textContent = inject_code;
(document.head || document.documentElement).appendChild(script_tag);
script_tag.parentNode.removeChild(script_tag);