The idea now is that a scroll group item can be added to the canvas which will causes its children to scroll in either or both
directions (horizontal or vertical). There are few complications: the position() of the ScrollGroup is ambiguous depending
on whether you want it with scroll taken into account or not, so Item::canvas_position() was added, which defaults to
the same value as Item::position() but is overridden by ScrollGroup to return the position independent of scrolling. This
method is used when translating between item/canvas/window coordinate systems.
Note that the basic idea is that we MOVE the scroll group when a scroll happens. This mirrors what happens in the GnomeCanvas,
where Nick Mainsbridge came up with a great idea that allowed unification of the time bar and track canvases.
Dragging regions vertically does the quantization BUT speed control is lacking and the region ends up on
a track that is still invisible ... to be fixed as the sun rises.
Many more changes than I would typically like in a single commit, but this was all very intertwined.
Vertical scrolling using track-stepping still to follow.
Best guess right now is that optimization does something bad when ceil() is called twice on a very large dbl-precision number,
which results in a zero (empty) redraw area. Without the removal of the redundant ceil & floor functions, no expose events
would be delivered to the canvas in an optimized build during drags (and maybe more).
gtkmm2ext/keyboard.cc has a special case to emit a signal on the key-up of
the modifier key used to adjust track heights in conjunction with the
scroll wheel, so that the same track continues to be resized even when
it's shrunk to no longer be under the mouse cursor. However, this code
assumed that the modifier key for this was <Shift>.
Fix it to use the event->state bit corresponding to
ScrollZoomVerticalModifier instead, and rename the relevant functions to
clarify that it's the 'zoom vertical' modifier key they're dealing with.
Partially fixes#5610.
when using ImportDistinctChannels, correctly name regions so that playlists for each channel/track
are also named differently, and thus reloaded properly when the session is reloaded.
gtkmm2ext/keyboard.cc has a special case to emit a signal on the key-up of
the modifier key used to adjust track heights in conjunction with the
scroll wheel, so that the same track continues to be resized even when
it's shrunk to no longer be under the mouse cursor. However, this code
assumed that the modifier key for this was <Shift>.
Fix it to use the event->state bit corresponding to
ScrollZoomVerticalModifier instead, and rename the relevant functions to
clarify that it's the 'zoom vertical' modifier key they're dealing with.
Partially fixes#5610.
when using ImportDistinctChannels, correctly name regions so that playlists for each channel/track
are also named differently, and thus reloaded properly when the session is reloaded.
