La forma correcta, tal como dice
Neftali sería:
Código Delphi
[-]
constructor MyClass.Create(AOwner: TComponent);
begin
inherited;
FTheForm := AOwner;
FOldResize := FTheForm.OnResize;
FTheForm.OnResize := MyOnResize
end;
procedure MyClass.MyOnResize(Sender: TObject);
begin
if Assigned(FOldResize) then
FOldResize(Sender)
end;
Ahora, si tu clase es un componente, la asignación del evento deberías hacerla redefiniendo el método
Loaded:
Código Delphi
[-]
MyClass = class(TComponent)
protected
procedure Loaded; override;
end;
implementation
procedure MyClass.Loaded;
begin
inherited;
if not (csDesigning in ComponentState) then
begin
FOldResize := FTheForm.OnResize;
FTheForm.OnResize := MyOnResize
end
end;
Saludos...