I am having Ubuntu 13.04 and 13.10. I have no problem with 13.04

In 13.10 I found that, when I tried to drag my window up across my standard dual-screen setup, it gets *jammed/stopped* when it goes as high as the top menu bar and won't go higher into my other screen that's configured from *system-settings->displays* to be right *above the current one*. 

In another word, My external monitor is positioned as *above* my internal laptop's screen, and I'm trying to drag my window *up* from my laptop screen into my external monitor screen. Dragging a window in reverse direction, e.g. *down* from external screen to my laptop screen is totaly fine.

I disabled maximizing at top screen edge (from CCSM) but still window won't drag up through the lower screen's top edge. I thought this might be related to some kind of snapping but I don't see any options for this in `compiz-config`. 

could this be about unity's menu bar? Or anything else?