Flex redrawing background when Scrolling, degrafa: How ?.

Hi Everyone, I am using a canvas which has a degrafa background, so far so good. However when scrolling apears the background (degrafa grid) does not get redrawn. In the code the bg strokes are linked to the container height. The thing is container.height does not change even when scrolling. How do i get the heigh of the whole area so i can set the new height to my degrafa background ?

it looks like this.

 <mx:Canvas id="blackBoard"
       width="100%" 
       height="100%" 
       x="0" 
       y="0" 
       backgroundColor="#444444"
       clipContent="true">

    <!-- Degrafa Surface   -->
    <degrafa:Surface id="boardSurfaceContainer">
            <degrafa:strokes>
                <degrafa:SolidStroke    id="whiteStroke"
                                        color="#EEE"
                                        weight="1"
                                        alpha=".2"/>
            </degrafa:strokes>

            <!-- Grid drawing -->
            <degrafa:GeometryGroup id="grid">
                <degrafa:VerticalLineRepeater   count="{blackBoard.width / ApplicationFacade.settings.GRID_SIZE}"
                                                stroke="{whiteStroke}"
                                                x="0"
                                                y="0"
                                                y1="{blackBoard.height}"
                                                offsetX="0"
                                                offsetY="0"
                                                moveOffsetX="{ApplicationFacade.settings.GRID_SIZE}"
                                                moveOffsetY="0"/>

                <degrafa:HorizontalLineRepeater count="{blackBoard.height / ApplicationFacade.settings.GRID_SIZE}"
                                                stroke="{whiteStroke}"
                                                x="0"
                                                y="0"
                                                x1="{blackBoard.width}"
                                                offsetX="0"
                                                offsetY="0"
                                                moveOffsetX="0"
                                                moveOffsetY="{ApplicationFacade.settings.GRID_SIZE}"/>

            </degrafa:GeometryGroup>       

        </degrafa:Surface>

From stackoverflow

• 

  

  http://img58.imageshack.us/my.php?image=board1or1.png

  http://img395.imageshack.us/my.php?image=board2nh0.png

• I just had to use the scroll position in the degrafa property binding

              <degrafa:VerticalLineRepeater   count="{(blackBoard.width + blackBoard.horizontalScrollPosition)/ ApplicationFacade.settings.GRID_SIZE}"
                                              stroke="{whiteStroke}"
                                              x="0"
                                              y="0"
                                              y1="{blackBoard.height + blackBoard.verticalScrollPosition}"
                                              offsetX="0"
                                              offsetY="0"
                                              moveOffsetX="{ApplicationFacade.settings.GRID_SIZE}"
                                              moveOffsetY="0"/>