This generic hook function is called whenever a grid grob is edited
via grid.edit or editGrob.
This provides an opportunity for customising the editing of a
new class derived from grob (or gTree).
editDetails(x, specs)A grid grob.
A list of named elements. The names indicate the grob slots to modify and the values are the new values for the slots.
The function MUST return the modified grob.
This function is called by 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.