Huseyin Ciftci wrote:

> How can i hide my application's taskbar icon? i tried this
>     application.Initialize;
>     application.MainFormOnTaskbar := false;
> but it didn't work.

With Delphi 2007, a new property of the Application object, the
MainFormOnTaskbar property controls how Windows taskbar buttons are
handled by VCL.


If MainFormOnTaskbar is true, a taskbar button represents the
application's main form and displays its caption. If false, a taskbar
button represents the application's (hidden) main window and bears the
application's Title.


By design, the MainFormOnTaskbar property is set to true for any new
Delphi 2007 application. You can change this value by editing the
projects (DPR) source code. MainFormOnTaskBar should be set after
Application.Initialize and before main form creation.




With Delphi versions up to Delphi 2007 a simple tweak to the
application's window style using the SetWindowLong API call allowed you
to hide the taskbar button (Delphi <= 2006).


This code no longer works with Delphi 2007! 
Hide the Taskbar button for Delphi 2007
With Delphi 2007, to hide the taskbar button you'll need a few code
lines: Set MainFormOnTaskBar to FALSE
Call 
ShowWindow(Application.Handle, SW_HIDE); 
inside the main form's OnShow event handler.
Call 
ShowWindow(Application.Handle, SW_HIDE); 
inside the main form's OnActivate event handler.