Fixed rack width and scroll

[gthibert]

It could be nice to be able to lock rack width, so when a patch goes beyond the rack vertical space, a vertical scroll bar appears, allowing to scroll the rack up and down...

It's a bit confusing when, in a live situation, I add a patch and the rack width double and every other racks are pushed to the right.

[CREDO]

+1
Similarly, it would be nice for the Settings panel to scroll instead too - especially frustrating selecting objects w/design tab.

[senso]

the vertical scroll bar is not actually implemented, but I'm thinking on a solution.
but don't forget that in usine it's recommended to minimize patches as much as we can.