made frequency param on enableMouseOver optional

Signed-off-by: Grant Skinner <info@gskinner.com>

Author: gskinner

VERSIONS.txt

@@ -3,6 +3,7 @@ Version 0.4.1 [Not released]
 - fixed a problem with preloading sprite sheet images when using tile based sheets
 - worked around a bug in Safari with addFlippedFrames
 - added setChildIndex(), swapChildrenAt(), and swapChildren() to Container
+- made frequency param on enableMouseOver optional
 
 
 Version 0.4 [Nov 30, 2011] 

src/easeljs/display/Stage.js

@@ -304,17 +304,18 @@ var p = Stage.prototype = new Container();
 	/**
 	 * Enables or disables (by passing a frequency of 0) mouse over handlers (onMouseOver and onMouseOut) for this stage's display
 	 * list. These events can be expensive to generate, so they are disabled by default, and the frequency of the events
-	 * can be controlled independently of mouse move events via the frequency parameter.
+	 * can be controlled independently of mouse move events via the optional frequency parameter.
 	 * @method enableMouseOver
-	 * @param {Number} frequency The maximum number of times per second to broadcast mouse over/out events. Set to 0 to disable mouse
-	 * over events completely. Maximum is 50. A lower frequency is less responsive, but uses less CPU.
+	 * @param {Number} frequency Optional param specifying the maximum number of times per second to broadcast mouse over/out events. Set to 0 to disable mouse
+	 * over events completely. Maximum is 50. A lower frequency is less responsive, but uses less CPU. Default is 20.
 	 **/
 	p.enableMouseOver = function(frequency) {
 		if (this._mouseOverIntervalID) {
 			clearInterval(this._mouseOverIntervalID);
 			this._mouseOverIntervalID = null;
 		}
-		if (frequency <= 0) { return; }
+		if (frequency == null) { frequency = 20; }
+		else if (frequency <= 0) { return; }
 		var o = this;
 		this._mouseOverIntervalID = setInterval(function(){ o._testMouseOver(); }, 1000/Math.min(50,frequency));
 		this._mouseOverX = NaN;