How to modify the GraphicsNode of GVT in apache batik?

[ma zhenduo <ma...@yahoo.com>]

Hi,
    I am working with apache batik1.1.1.
    In my program,  There are Steps:
        1. parse the svg file to the SvgSaxDocument,
        2. build SvgSaxDocument to the tree of GraphicsNode
        3. transcoder the tree of GraphicsNode to JPEGImage and send to
user.
        4. find out the GraphicsNode selected by user on the tree generated
in Step2.
        5. modify these selected GraphicsNode and redo the Step 3.

    my questions is:
        1. How to modify a GraphicsNode to show ideally that it had been
selected?
        2. If I can easyly change the fill color of a GraphicsNode?
        3. Now, I had maken a Filter Object by copying and modifying the
code of  some FilterBridges.
            That filter can modify the fill color like SpecularLight Filter.
            Then I call the setFilter() mothed, if there are not a filter
ever, all is right.
            But if there are a filter ever, all get bad. Example, if there
are a feOffset Filter to shift image ever,
            after I set my filter, the image can not be shift.

    I am sorry, the upper questions must be very mess.
    I eager the whole perfect blue print and any help from you.
Thanks,
ZD Ma.