That almost helps, although I now have a new slightly more complicated example!
If you look at the file I have uploaded, my new problem relates to the fact that I have pinned a movieclip that contains "blah", "bottom box 1,2,3&4" & "box1,2,3&4 of which box 4 is behind a mask covering box1,2&3)" to the middle of the stage so everything inside there moves together.
Now, inside that movieclip, if you were to click "bottom box 2", all the boxes would slide left and "box 2" would stop where "box 1" used to be. Unfortunately when I resize the window LiquidStage ignores the mask and shifts everything across.... is there any way I can get round that without breaking apart my movieclip and repositioning everything individually?
(I've added CarusoTop.swf. Not sure if you can view it, but that is the working example of what is happening)