lightweight DisplayImplJ2D; disableAction and enableAction for DisplayImpl

The Components generated for DisplayImplJ2D are now lightweight
and hence will work well with swing JComponents.

We cannot do this for DisplayImplJ3D however - that depends on
Sun (and it will be very difficult for them because the OpenGL
underneath Java3D requires a heavyweight window).

I have added methods disableAction() and enableAction() to
DisplayImpl (actually to ActionImpl, which is extended by both
DisplayImpl and CellImpl), so that applications can make a sequence
of changes to a display without triggering a lot of intermediate
rendering.  Specifically:

  // add and remove DataReferences
  // setRange() on ScalarMaps
  // changes to Controls

and the changes are made all at once, after the call to enableAction.

Bill Hibbard, SSEC, 1225 W. Dayton St., Madison, WI  53706
hibbard@xxxxxxxxxxxxxxxxx  608-263-4427  fax: 608-263-6738