Consider the following GVT node tree:

              +----+
              | N1 | BKGRND = new
              +----+
                /\
               /  \
              /    \
         +----+   +----+
         | N2 |   | N3 | Opacity=0.5
         +----+   +----+
          /|\       |  \
         .....      |   \
                    |    \
                  +----+ +----+
                  | N4 | | N5 | Filter = feOffset(src=Background)
                  +----+ +----+


N1.paint(G)
  Calls N2.paint(G)
  N2.paint does it's thing...