Change PaperScope#install() to be clever about project, view and tool references and link them through a getter to their current state in PaperScope.

src/core/PaperScope.js

@@ -126,10 +126,22 @@ var PaperScope = this.PaperScope = Base.extend(/** @lends PaperScope# */{
 	 * paper.install(window);
 	 */
 	install: function(scope) {
+		// Define project, view and tool as getters, so they are kept up to date
+		var that = this;
+		Base.each(['project', 'view', 'tool'], function(key) {
+			Base.define(scope, key, {
+				configurable: true,
+				writable: true,
+				get: function() {
+					return that[key];
+				}
+			});
+		});
 		// Use scope as side-car (= 'this' inside iterator), and have it
 		// returned at the end.
 		return Base.each(this, function(value, key) {
-			this[key] = value;
+			if (!(key in this))
+				this[key] = value;
 		}, scope);
 	},