.
.
.
Tform1 = class (Tform)
         // All the components on your form
         Button1. : Tbutton;
         .
         .
         .
         Private
         procedure CMMouseEnter(var Message : Tmessage); 
                   message CM_MOUSEENTER;
         procedure CMMouseLeave(var Message : TMessage); 
                   message CM_MOUSELEAVE;
         procedure WMActive(var Message : TWMActivate); 
                   message WM_ACTIVE;
         .
         .
         .
         end;
.
.
.

Var
  From1 : Tform1;
implementation
...

procedure Tform1.CMMouseEnter (var Message : TMessage);
...
begin
  ....
end;

procedure Tform1.CMMouseLeave; {(var Message : Tmessage); 
                                You do not have to write it again
                                after your first declaration. }
...
begin
  ....
end;

procedure Tform1.WMActive(var Message : TWMActive);
...
begin
end;

...

end.