// Sets pen color to clRed for all selected objects.
for i:=0 to ImageEnVect1.SelObjectsCount-1 do
  ImageEnVect1.ObjPenColor[ ImageEnVect1.SelObjects[i] ] := clGreen;

// changes to red pen color for each object
for i := 0 to ImageEnVect1.ObjectsCount - 1 do
begin
  hobj := ImageEnVect1.GetObjFromIndex( i );
  ImageEnVect1.ObjPenColor[ hobj ] := clRed;
end;

// set pen color to clRed for the first object that has ObjName[]='Jack'
var
  hobj:integer;
begin
...
  hobj:=ImageEnVect1.GetObjFromName('Jack');
  ImageEnVect1.ObjPenColor[hobj]:=clRed;
..
end;

function IsSelObject(hobj: integer): boolean;

Description
IsSelObject returns true if hobj object is selected.
The last inserted object is always selected.