[MU4 Task] Box selection for notes

[ShibuyaCyana]

Task description Make it possible to make box selection for individual notes, like what we can do in piano rolls.

Usecase Say I want to make measure 1 into measure 2, that is to select all the A notes and move them down for a whole step

In MS3 it's almost like I can do this with shift + left drag, but when release, it's the whole bar that become selected:

In MS4, while shift + left drag is working for things like hairpins, trying to do shift + drag on staff lines results in an instant selection of the whole bar:

While I can do it via selection menu or ctrl and clicking, making box selection and drag them down would be more convenient.