demo to illustrate how to implement calibrate()
and grid.locator() for a numerical matrix. This is just a stub
to be replaced by the user's actual program.
numeric number of seconds to sleep to avoid potential race condition
Details
this package emulates edit() but allows full control
over formatting and management of the edited matrix.
sleepTime parameter can be set to nonzero (suggest trying sleepTime=0.5) in case a complicated
graphic causes a race condition evidenced by incomplete redrawing of the window. Too large a value
might cause a noticeable annoying delay in redrawing the window.