Morpho

In the header row of the data table, if the user tries to drag the separators to
make the columns wider/narrower, the column is selected. This could be bad if
the user has already made a selection of cells in the table - the selection
would be lost. Also, MetaViewer changes from Entity to Attribute when col is
selected (less of a problem, but still annoying if user is only trying to resize
columns)

The column should be selected only if the user clicks on the header; if the user
clicks and drags the separator, the column should not be selected (see
mouselistener code for table header in file->open dialog: this sorts if the user
clicks, but resizes without sorting if the user drags the dividers)