Dragging a MovieClip is a very common task in a Flash application or movie. The code to achieve this result is fairly simple

For this example, the dragging code will be assigned within a function for portability

function initDragger(mc:MovieClip):void
{	
	...	
}

Here is the contents of that function which is setup using event listeners. The MouseEvent Class has a custom function attached where the drag code is called.

mc.addEventListener(MouseEvent.MOUSE_DOWN, function (e:MouseEvent):void
{
	e.currentTarget.startDrag();
});
mc.addEventListener(MouseEvent.MOUSE_UP, function (e:MouseEvent):void
{
	e.currentTarget.stopDrag();
});

The final step is to make a call to the newly created function and test it all out

function initDragger(mc:MovieClip):void
{	
	mc.addEventListener(MouseEvent.MOUSE_DOWN, function (e:MouseEvent):void
	{
		e.currentTarget.startDrag();
	});
	mc.addEventListener(MouseEvent.MOUSE_UP, function (e:MouseEvent):void
	{
		e.currentTarget.stopDrag();
	});
	
}

// Set up drag
initDragger(boxMC);

Update: After this tutorial was finished it was brought to my attention that inline functions can cause a memory leak over time. This is obviously not the desired result, so here is the same code modified to prevent that memory leak.

function initDragger(mc:MovieClip):void
{
	mc.addEventListener(MouseEvent.MOUSE_DOWN, mouseDownHandler);
	mc.addEventListener(MouseEvent.MOUSE_UP, mouseUpHandler);
}

function mouseDownHandler(e:MouseEvent):void
{
	e.currentTarget.startDrag();
}
function mouseUpHandler(e:MouseEvent):void
{
	e.currentTarget.stopDrag();
}

// Set up drag
initDragger(boxMC);