combines selection related editor properties with the current editor selection.
The related editor properties are:
mouse mode,
zoom setting,
left frame of the canvas,
y origin of the canvas.
Selection state now includes region views (storing the underlying region id)
and time.
This patch also fixes a region mute undo bug.
Using _last_pointer_frame breaks when dragging to the left of the canvas, because we clamp
the value of the frame to >= 0. Motion would step once the pointer crossed the left edge
of the canvas because the frame value would always be zero.
This is not a problem when using the pointer x,y values which end up appropriately negative
under all conditions.
This lets us get a more explicit handle on time conversions, and is the main
step towards using actual beat:tick time and getting away from floating point
precision problems.
No functional changes in this one (for easier auditing), but towards having
round up/down only if necessary modes, rather than kludging around that
situation with a double round as we do currently.
It was much too easy to accidentally create MIDI regions in object mode. If
the user isn't in draw mode anyway, then even after creating a region, they
can't put notes in it, so I don't think we've lost any discoverability here.
Specifically, when pivoting from forwards to backwards (around the drag start
point), the note length was too long. Setting both the start and end x
coordinates of the rect every time to the right value does the right thing.
Use RegionSelection for MIDI regions as well, since the old dumb stub didn't do
some things correctly. There's probably no reason to have a separate class for
this at all, and some good ones for putting all regions in the same selection,
so we should probably do that. For now they are still separate in the
selection but use the same base class.
TODO: needs undo. only works in top quarter of automation lane. selection model feels weird sometimes. needs to show gain curve when you are using Range tool
(1) if we're dragging over the drop zone, then x-axis motion is irrelevant for threshold-of-move
(2) store original time axis view of a dragged region so that if we create a new track with the region drag, it can be the same height
