How to create a function which returns a value from a form

Problem/Question/Abstract:

I need a function to show a form and getting back a value, like InputBox or similar. How can I do this?

Answer:

type
  TMyForm {set positions and captions as you desire}
  Edit1: TEdit;
  ButtonOK: TBitBtn; {set Kind property to bkOK}
  ButtonCancel: TBitBtn; {set Kind property to bkCancel}
  private
    public
end;

{var MyForm:TMyForm; I do not use it, so I get rid of it}

function GetMyValue: string;

implementation

function GetMyValue(DefaultValue: string): string;
{not part of the TMyForm class}
begin
  with TMyForm.Create(Application) do
  try
    result := TMyValue.Create;
    result := DefaultValue;
    Edit1.Text := DefaultValue;
    if ShowModal = mrOK then
      result := Edit1.Text;
  finally
    Release;
  end;
end;