Class: TEgFireGridColumn
property ImageOnSelectedOnly: Boolean;When True, the column’s icon is shown only in the active
cell (the active row with egoRowSelect). See the grid’s ImageOnSelectedOnly.
Until it is assigned, the column follows the grid’s ImageOnSelectedOnly,
and changes with it. Assigning it, even to the value it already shows,
gives the column its own value (cvImageOnSelectedOnly in AssignedValues),
which the grid’s no longer changes; RestoreDefaults
makes it follow the grid again.