jQuery ui - slider - Safari 3.0.4 Mac & Win

I implemented a vertical scrollbar using the slider ui. There is a handle at the top which onclick moves the slider up (call it top-handle) and another handle at the bottom which onclick moves the slider down (call it bottom-handle). Both use the moveTo method of the slider). There is another handle to slide up and down (call it the slider-handle) - so it's a classical scrollbar with three handles.

When initialized, for some reason, the slider-handle is positioned at -6, this means at the top, at the minimal value.

In Safari 3.0.4 the strange thing happens, when clicking on the top-handle right after initialization: nothing happens right onclick (as expected!) but when you then click on the slider-handle, it moves up, although already positioned at the minimum value, so it will hide the top-handle. After sliding the slider-handle to the maximum position and back, everything works perfect as long as you don't position the slider-handle in its initial position again and then click again on the top-handle - if you do so, exactly the same thing happens with the slider-handle as described before.

It means: using "moveTo -=" in Safari 3.0.4 when the slider-handle is in its minimal position breaks the slider somehow.