After running several tests using 3 different monitors of the same model, Apple 17" Studio and getting the same problem (color dashes flashing in dark backgrounds); problem that doesn't show when using the same 3 monitors with Mac OSX, it might be concluded, or at least one can make the hypothesis, that this particular monitor is not supported by MorphOS 3.0.
Of course, this need to be restested and validaded by someone else with more experience and using the same setup: Mac Mini G4, connected to the 17" Studio display using a Mini DVI-DVI, DVI-ADC adapter (which is nowadays more expensive than the monitor. The Mini DVI-DVI, DVI-ADC is a 3-way cable with a power din-type connector, USB and ADC connection.
So stay away from this monitor for now.