grid.edit or editGrob.
This provides an opportunity for customising the editing of a
new class derived from grob (or gTree).editDetails(x, specs)grid.edit and editGrob.
A method should be written for classes derived from grob or gTree
if a change in a slot has an effect on other slots in the grob or
children of a gTree (e.g., see grid:::editDetails.xaxis). Note that the slot already has the new value.grid.edit