MakeVPort() has to notify the Fx of any changes - eg switching to BeamSync
modes, or enabling LACE (esp for VideoControl() effects). Will probably need to
keep each FxHandle in a list so that the caches can be altered.

VideoControl() will need to OR in gb_system_bplcon0. CAn do this if MakeVPOrt()
changes the fvch caches.

Check error of MakeVPort() in LineControl. May need some way to return an error
from the Install vectors.

LineControl doesn't work if the screen is opened with SA_Left non-zero.


The sample program for specialfx should not be poking the hardware within its
interrupt server. Kinda defeats the purpose of the library.

GfxBase->ActiView ain't safe to access

Check the DIPF_IS_NATIVE field of the ModeID of the ViewPort.

SFX_CollisionControl

MrgCop() patch and RemoveFX() both FreeMem the copied copperlists whilst it is
being displayed. Check for this!!

MrgCop() patch does not lock the ActiViewCprSemaphore. May need to do this.

When LineControl is coerced, MrgCop() may double some of the WAITs.  This means
that gaps of one line between WAITs become two lines.  You could walk the
copperlist in the RebuildLineControl() vector and change the WAIT instructions.
