Attach a function to an event handler

I think this is what you want,

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Label1: TLabel;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
    procedure WriteHallo;
  end;

var
  Form1: TForm1;

implementation

uses Unit2;

{$R *.DFM}

procedure TForm1.Button1Click(Sender: TObject);
begin
 Form2.ShowModal;
end;

procedure TForm1.WriteHallo;
begin
 label1.Caption := 'Hello, Tom is this what you want?';
end;

end.

unit Unit2;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  ExtCtrls, StdCtrls;

type
  TForm2 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form2: TForm2;

implementation

uses Unit1; { <-------- THIS NEEDS TO BE HERE }

{$R *.DFM}

procedure TForm2.Button1Click(Sender: TObject);
begin
 {Add Unit1 to uses list}
 Form1.WriteHallo;
end;

end.

?? I don't follow what you are trying.

What i want to do in thre form create is:

TPanel.OnDblClick := MyFunction;

where my function is a function declared in another unit.

Thanks,

Tom.

Ah, now I get it.
But my solution works too. If you push the button in Form2 then in Form1 the text in caption1 will be changed (thanks to procedure WriteHallo) -> look at form1 after pushing button on form2.

If you put in your TPanel.OnDblClick the following code :
FormName.FunctionName then this will be activated when you double click on tpanel. This is the easiest way to do it.

Ok, the later makes sense, I'll do it that way, I should have thought of that. Put an answer in so I can grade you. Tom.

calling the function in a handler was the way to go rather than trying to attach to the handler.