Page frame/margin restrictions?

In this Discover Dorico session, John covers how Dorico calculates spacing.

Basically, it adds up the heights of staves, the minimum gaps between them (as set in Layout Options), any extra space needed for “stuff that extends above/below staves” (like high/low notes, dynamics etc), the notations and their padding – and compares that to the amount of space inside the music frame, minus the frame padding at the top/and bottom.

If the “stuff inside the frame” requires more vertical space than “the space available inside the frame”, you get an overfull frame and a >100% indication in the frame fullness indicator. Something as simple as slightly reducing the minimum gaps between staves/systems by 1/8 or 1/4 can eliminate this, depending on the circumstances.