How do I get a bounding box for the current selection?

I'd like to do fancy things the selection indicator. How do I get the bounding box for the currently selected characters?

This was non-trivial. First, a selection may require more than one rectangle. Next, there's no convenient way to do it.

Here's what I had to do:

        var start:int = op.activePosition < op.anchorPosition ? op.activePosition : op.anchorPosition;
        var end:int = op.activePosition > op.anchorPosition ? op.activePosition : op.anchorPosition;

        var textFlow:TextFlow = this.textFlow;
        var rectangles:Dictionary = new Dictionary();

        // For each selected character, make a box
        for( var i:int=start; i < end; i++) {

            var flowLine:TextFlowLine = textFlow.flowComposer.findLineAtPosition( i, true );

            if( rectangles[ flowLine.absoluteStart ] == null ) {
                rectangles[ flowLine.absoluteStart ] = new Rectangle();
                (rectangles[ flowLine.absoluteStart ] as Rectangle).x = 0xffffff;
                (rectangles[ flowLine.absoluteStart ] as Rectangle).right = 0;
            }
            var currentRect:Rectangle = rectangles[ flowLine.absoluteStart ];

            var textLine:TextLine = flowLine.getTextLine(true);
            var atomIndex:int = textLine.getAtomIndexAtCharIndex( i );
            if( atomIndex >= 0) {
                var atomBounds:Rectangle = textLine.getAtomBounds( atomIndex );

                var pt:Point = this.globalToLocal( textLine.localToGlobal( new Point( atomBounds.left, atomBounds.top ) ) );                    
                if( pt.x <= currentRect.left ) {
                    currentRect.left = pt.x;
                    currentRect.top = pt.y;
                }

                pt = this.globalToLocal( textLine.localToGlobal( new Point( atomBounds.right, atomBounds.bottom) ) );
                if( pt.x >= currentRect.right ) {
                    currentRect.right = pt.x;
                    currentRect.bottom = pt.y;
                }                   
            }
        } 
        return rectangles;