Setting and Moving Object Registration Point
Flash CS4 Tutorial
How to Set and/or Move Flash Object Registration Point
A symbol's registration point determines it's stage placement, scale center and rotation point in ActionScript. The registration point is different than the pivot point. The pivot point is set when using the Free Transform tool.
Whenever you create a symbol, there is an icon in the dialog box that allows you to set the registration point. If you decide to move the registration point once it is created you will need to follow these steps.
In a new Flash document, Use the Rectangle tool (r key) to create a shape on the stage.
Select the shape and press F8 to convert it to a Movie Symbol.
Name your symbol and set the registration to the upper left corner of the symbol.
Select the object on the stage and note the small cross hair in the upper left corner of the object.
Double-click the object to enter the object editing mode.
Drag the rectangle to reposition the registration point.
A quick way to set the registration point to the center of the object is to open the Align panel (Cmd/k (PC - Ctrl/k).
Set the To Stage icon to medium gray and press Align Vertical Center and Align Horizontal Center.