How to hide an application from taskbar in Windows 7?

Question

I would like to hide an application from the Windows 7 taskbar.

I want to make something like a toolbar on the edge of the screen which does certain things when the

Answer 1

your application main form is normally created in the dpr so open the dpr and look for the line that creates the main form.

// add this line first
// blank app title will prevent app from showing in the applications list in task manager
Application.Title := '';

// this line is already in the dpr and creates the main form, the class will differ
Application.CreateForm(TMainForm, Result);

// make the main form invisible to windows taskbar/task switcher
i := GetWindowLong(Application.Handle, GWL_EXSTYLE);
SetWindowLong(Application.Handle, GWL_EXSTYLE, i OR WS_EX_TOOLWINDOW AND NOT WS_EX_APPWINDOW);

i know this works on XP and 7. i'm guessing it's good for 8 as well. this adds the tool window flag and removes the appwindow flag so i guess if you're not interested in the toolwindow flag you can leave out the following part

i OR WS_EX_TOOLWINDOW

Answer 2

You can override the main form's CreateParam to remove the flag that forces the taskbar button (WS_EX_APPWINDOW) and additionally make the form owned by the application window. That's doing the opposite of the requirement for the shell to place a taskbar button for a window. From "Managing Taskbar Buttons":

[..] To ensure that the window button is placed on the taskbar, create an unowned window with the WS_EX_APPWINDOW extended style. [..]

Sample:

type
  TForm1 = class(TForm)
  protected
    procedure CreateParams(var Params: TCreateParams); override;
  end;

procedure TForm1.CreateParams(var Params: TCreateParams);
begin
  inherited;
  Params.ExStyle := Params.ExStyle and not WS_EX_APPWINDOW;
  Params.WndParent := Application.Handle;
end;

Don't change the state of MainFormOnTaskbar property of the 'Application' from its default 'True' if you use this method.

You can also remove the second line (..WndParent := ..) and instead set PopupMode of the form to pmExplicit in the object inspector to same effect.

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BTW, here's the documentation quote from the same topic for the solution TLama posted:

To prevent the window button from being placed on the taskbar, [...] As an alternative, you can create a hidden window and make this hidden window the owner of your visible window.

When you set MainFormOnTaskbar to false, the main form is owned by the application window by VCL design. And if you hide the application window, the requirement is fulfilled.

Answer 3

Try to use a tricky way described in this article:

Set the MainFormOnTaskBar to False in your project file. Then try to hide the application window from the main form's OnShow and OnActivate event handlers. So your project might look like follows:

Project1.dpr:

program Project1;

uses
  Forms,
  Unit1 in 'Unit1.pas' {Form1};

{$R *.res}

begin
  Application.Initialize;
  Application.MainFormOnTaskbar := False;
  Application.CreateForm(TForm1, Form1);
  Application.Run;
end.

Unit1.pas:

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    procedure FormShow(Sender: TObject);
    procedure FormActivate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormShow(Sender: TObject);
begin
  ShowWindow(Application.Handle, SW_HIDE);
end;

procedure TForm1.FormActivate(Sender: TObject);
begin
  ShowWindow(Application.Handle, SW_HIDE);
end;

end.