Patch from Andy Ross:

Patch from Andy Ross:

Actually, I think I'm off the hook here; the problem is pre-existing.
What's happening is that the x/y offsets enter the modelview matrix at
line 346 in the current panel.cxx.  But note that the same
transformation also occurs before each instrument rendered at line
403.  What's happening is that the instruments are double-translated
relative to the background.

Unless I'm not understanding something, the one inside the instrument
render loop looks unnecessary.  Removing it fixes the issue and
doesn't cause any bugs that I can find.  It also fixes a bug where you
could scroll the instruments on top of the 3D panel, where the offsets
are supposed to be ignored. :)

Attached is a new panel.cxx which fixes that bug, and substantially
simplifies the virtual panel code (the matrix inversion that I thought
was needed wasn't, but there were some offsetting scale bugs that hid
the problem).