Only last added Delphi component does action - delphi

Question

I created my own component (it like a button which can move) in Delphi, installed it. Then I create a new project and new from there and added few new my component elements. But only last one added is able to move! Others not. Why does it happen? How could I fix it?
Here's the component code:
unit ModifiedButton;
interface
uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
StdCtrls, ExtCtrls;
var Timer: TTimer;
type
TSpeed = (Slow,Normal,Fast);
TModifiedButton = class(TButton)
private
{ Private declarations }
FCount:integer;
Velocity:integer;
FSpeed:TSpeed;
protected
{ Protected declarations }
procedure Click;override;
procedure Move(Vel:Integer);
procedure OnTimer(Sender: TObject);
public
{ Public declarations }
procedure ShowCount;
published
{ Published declarations }
property Count:integer read FCount write FCount;
property Speed: TSpeed read FSpeed write FSpeed;
constructor Create(aowner:Tcomponent); override;
end;
procedure Register;
implementation
procedure Register;
begin
RegisterComponents('MyComponents', [TModifiedButton]);
end;
{ TModifiedButton }
procedure TModifiedButton.Click;
begin
inherited Click;
FCount:=FCount+1;
if (Speed = Slow) then
Velocity:=2;
if (Speed = Normal) then
Velocity:=10;
if (Speed = Fast) then
Velocity:= 20;
Timer.Enabled:=True;
end;
constructor TModifiedButton.Create(aowner: Tcomponent);
begin
inherited Create(aowner);
Timer:=TTimer.Create(self);
Timer.Enabled:=false;
Timer.OnTimer:=OnTimer;
Timer.Interval:=10;
end;
procedure TModifiedButton.Move(Vel: Integer);
begin
Left:=Left + Vel;
end;
procedure TModifiedButton.OnTimer(Sender: TObject);
begin
Move(Velocity);
end;
procedure TModifiedButton.ShowCount;
begin
ShowMessage('You cliked '+ caption+' for '+inttostr(FCount)+' times');
end;
end
.

Answer 1

Since the Timer is a global variable, each new button you create will overwrite the OnTimer event handler of the previous button. Solution, make the Timer a member of your TModifiedButton class:
unit ModifiedButton;
interface
uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
StdCtrls, ExtCtrls;
type
TSpeed = (Slow,Normal,Fast);
TModifiedButton = class(TButton)
private
{ Private declarations }
FCount:integer;
Velocity:integer;
FSpeed:TSpeed;
Timer: TTimer;
protected
{ Protected declarations }
procedure Click;override;
procedure Move(Vel:Integer);
procedure OnTimer(Sender: TObject);
public
{ Public declarations }
procedure ShowCount;
published
{ Published declarations }
property Count:integer read FCount write FCount;
property Speed: TSpeed read FSpeed write FSpeed;
constructor Create(aowner:Tcomponent); override;
destructor Destroy; override;
end;
procedure Register;
implementation
{ TModifiedButton }
procedure TModifiedButton.Click;
begin
inherited Click;
FCount:=FCount+1;
Case Speed of
Slow : Velocity:=2;
Normal : Velocity:=10;
Fast : Velocity:= 20;
end;
Timer.Enabled:=True;
end;
procedure TModifiedButton.Move(Vel: Integer);
begin
Left:=Left + Vel;
end;
procedure TModifiedButton.OnTimer(Sender: TObject);
begin
Move(Velocity);
end;
procedure TModifiedButton.ShowCount;
begin
ShowMessage(Format('You clicked %s for %d times', [Caption, FCount]));
end;
constructor TModifiedButton.Create(AOwner: Tcomponent);
begin
inherited Create(AOwner);
Timer := TTimer.Create(self);
Timer.Enabled:=false;
Timer.OnTimer:=OnTimer;
Timer.Interval:=10;
end;
destructor Destroy;
begin
Timer.Enabled := False;
Timer.Free;
end;
procedure Register;
begin
RegisterComponents('MyComponents', [TModifiedButton]);
end;
end.