multiple resizables acting strange

multiple resizables acting strange

Hi there everyone,

I'm trying to place multiple resizable and draggable div's on one page that move (vertically) inside their own parent div.
you can take a look at http://bit.ly/bCutBE

However, these div's act really strange when I want to resize them, especially from the north side, they kind of move out of the screen very fast, while they shouldn't be able to get outside the parent div.
I only want the div to be able to move and resize vertically inside it's parent, the dragging-part works pretty good, but the resize part give this problem.

I can't really describe it better than this, but take a look for yourself and it will be clear immediately when you try to resize one of the coloured div's: move it a little downwards and try to resize it from the north side.

I hope someone can help me with this...