TTouchKeyboard: send keystroke to other program?

TTouchKeyboard sends the keys to the current control focused: so if you have a TEdit with the focus, the TEdit will receive the key...

You can create a form which contains the TTouchKeyboard and add this procedure:

  protected
    procedure CreateParams(var Params: TCreateParams); override;

...

procedure TForm1.CreateParams(var Params: TCreateParams);
begin
  inherited CreateParams(Params);
  with Params do
  begin
    ExStyle   := ExStyle or WS_EX_NOACTIVATE;
    WndParent := GetDesktopwindow;
  end;
end;

Your form can't have the focus... so, the key is sent to the previous focused control.