When using the mouse wheel inside a viewport (ListBox or Viewport directly) the vertical scroll bar is immediately scrolls to the upper left regardless of
the position of the scrolling / the amount scrolled.
This only happens in VST mode, in standalone mode it works fine (it also works fine in Mac standalone / AU / VST )
I've found that in the func. doMouseWheel() the line:
const float amount = jlimit (-1000.0f, 1000.0f, 0.5f * (short) HIWORD (wParam));
Always returns 1000 in the problematic cases.