[Fixed] Allow dragging over top and bottom queue buttons, moved top and bottom buttons to top and bottom of queue

[Tophness]

sorry, but I had to revert it as I didnt realize these arrows would be always visible even when not needed. Only a few people have that many tasks in the queue so that the scrollbar needs that kind of stuff. Please find a way to have these arrows displayed only if the scroll bar is visible.

It was always the case that the arrows would only appear if the queue length was at least 11 (literally if len(queue) > 11: ). Nothing #1457 did changed that, all it did was move the buttons to logical positions and added dragover events to them.

I've set it to 9 now. I think it made more sense with the original 11 it was always at, but up to you. It's a single digit variable to change it.

The scrollbars first appear at 9 queue items (10 total, but the 0th index one is added to the preview, not the queue), but while the scrollbar is visible at 9, the scrollbar doesn't do anything besides move down about 1 pixel (not even below the bottom queue item). If the scrollbar itself is redundant, so is a scroll to bottom shortcut.
At 10, the scroll to bottom button is still redundant. You can scroll below 1 queue item with the scrollbar or mouse, but there'd still be no point pressing "scroll to bottom", since you can already scroll that 1 item as fast or faster using the scrollbar or mouse wheel. Hence it was started at 11: the moment it becomes feasibly useful.