Basically, I want a group of buttons in which only one (the one you last clicked) can be on at a time.

What is the easiest way to do this?

Currently, this is the fastest way I can find, and I'm sure it isn't the fastest way.

Code:
package
{
	import flash.events.*;
	import flash.display.MovieClip;
	
	public class Fasdfs extends MovieClip
	{
		var buttonArr:Array;
		var i:int;
		
		public function Fasdfs()
		{
			buttonArr = new Array(5);
			buttonArr[0] = but0;
			buttonArr[1] = but1;
			buttonArr[2] = but2;
			buttonArr[3] = but3;
			buttonArr[4] = but4;
			
			for (i = 0;i < buttonArr.length;i++)
			{
				buttonArr[i].addEventListener(MouseEvent.CLICK,clicked1);
			}
		}
		function clicked1(e:MouseEvent):void
		{
			if (e.target.isOn)
			{
				for (i = 0;i < buttonArr.length;i++)
				{
					if (buttonArr[i] != e.target)
					{
						buttonArr[i].gotoAndStop(1);
					}
				}
			}
		}
	}
}
Code:
package
{
	import flash.events.*;
	import flash.display.MovieClip;
	
	public class SelectButton extends MovieClip
	{
		public var isOn:Boolean;
		public function SelectButton()
		{
			isOn = false;
			this.addEventListener(MouseEvent.CLICK,clicked);
		}
		function clicked(e:MouseEvent):void
		{
			isOn = true;
			this.gotoAndStop(2);
		}
	}
}
All the buttons on the stage have the SelectButton baseclass. GotoAndStop is there because each button (but0, but1, but2, etc) has a yellow frame and black frame, to visually show toggling.

Got a quicker solution?