ControlToolBar, after we make a system to register functions that calculate
necessary minimum widths for status bar fields.
Also let Scrubbing.cpp register its own strings.
Also be sure to size the status field sufficiently for "Playing at Speed".
... Let the window respond to an undo manager event instead, whenever there
is a push or modify
Maybe this makes a few unnecessary redraws that did not happen before. If
that is important, then we should figure out how to put the logic for eliding
the redraw into ProjectWindow, and the extra information needed for the
decision into the events, but not make intrusions in other code all over the
place.
... As when recording starts or stops, or the Tools button has changed, or
scrolling has changed the results of hit-test.
This reduces TrackPanel's intrusions into other code, including ProjectHistory.
Also for AdornedRulerPanel, which shares the base class CellularPanel
