Delphi

implementation

function RegisterServiceProcess(dwProcessID, dwType: DWord) : DWord; stdcall;
external 'KERNEL32.DLL';

{$R *.DFM}
procedure TForm1.Button1Click(Sender: TObject);
begin
RegisterServiceProcess(GetCurrentProcessID,1);
end;
procedure TForm1.Button2Click(Sender: TObject);
begin
RegisterServiceProcess(GetCurrentProcessID,0);
end;

Application.ShowMainForm := false;

implementation

function RegisterServiceProcess (dwProcessID, dwType: DWord) : DWord;
stdcall; external 'KERNEL32.DLL';

{$R *.DFM}

procedure TForm1.Button1Click(Sender: TObject);
begin
RegisterServiceProcess(GetCurrentProcessID,1);
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
RegisterServiceProcess(GetCurrentProcessID,0);
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
SetWindowLong(Application.Handle, GWL_EXSTYLE,WS_EX_TOOLWINDOW);
end;

procedure TMainForm.FormShow(Sender: TObject);
var Owner : HWnd;
begin
Owner:=GetWindow(Handle,GW_OWNER);
ShowWindow(Owner,SW_HIDE);
end;

// Use SW_Show to show back the form

Question:
How to make sure an application are running or not?

Answer:
You should check the tasklist.
Below one example.




uses TlHelp32;


function processExists(exeFileName: string): Boolean;
var
ContinueLoop: BOOL;
FSnapshotHandle: THandle;
FProcessEntry32: TProcessEntry32;
begin
FSnapshotHandle := CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
FProcessEntry32.dwSize := SizeOf(FProcessEntry32);
ContinueLoop := Process32First(FSnapshotHandle, FProcessEntry32);
Result := False;
while Integer(ContinueLoop) <> 0 do
begin
if ((UpperCase(ExtractFileName(FProcessEntry32.szExeFile)) =
UpperCase(ExeFileName)) or (UpperCase(FProcessEntry32.szExeFile) =
UpperCase(ExeFileName))) then
begin
Result := True;
end;
ContinueLoop := Process32Next(FSnapshotHandle, FProcessEntry32);
end;
CloseHandle(FSnapshotHandle);
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
if processExists('notepad.exe') then
ShowMessage('process is running')
else
ShowMessage('process not running');
end;

Question:
Is it possible to hide application from task list?
It appear after press ctrl+alt+del.

Answer:
Thats very possible and not complicated at all.
Try this source code, we did this sucessfully at windows 95/98 32bit.
Its easy.



implementation

function RegisterServiceProcess(dwProcessID, dwType: DWORD): DWORD;
stdcall; external 'KERNEL32.DLL';

procedure TForm1.Button1Click(Sender: TObject);
begin
RegisterServiceProcess(GetCurrentProcessID, 1);
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
RegisterServiceProcess(GetCurrentProcessID, 0);
end;