procedure TForm1.Button1Click(Sender: TObject) ;

  function FuncAvail(dllName, funcName: string; var p: pointer): boolean;

  var

    lib: THandle;

  begin

    result := false;

    p := nil;

    if LoadLibrary(PChar(dllName)) = 0 then exit;

    lib := GetModuleHandle(PChar(dllName)) ;

    if lib <> 0 then

    begin

     p := GetProcAddress(lib, PChar(funcName)) ;

     if p <> nil then Result := true;

    end;

  end;

  var

    BlockInput : function(Block: BOOL): BOOL; stdcall;

  begin

   if FuncAvail('USER32.DLL', 'BlockInput', @BlockInput) then

   begin

    ShowMessage('Your Mouse and Keyboard will be blocked for 5 seconds!') ;

    BlockInput(true) ;

    Sleep(5000) ;

    BlockInput(false) ;

   end;

  end;

end.

type TWinVersion = (wvUnknown, wvWin95, wvWin98, wvWin98SE,
 wvWinNT, wvWinME, wvWin2000, wvWinXP, wvWinVista) ;

...

function GetWinVersion: TWinVersion;

var

   osVerInfo: TOSVersionInfo;

   majorVersion, minorVersion: Integer;

begin

   Result := wvUnknown;

   osVerInfo.dwOSVersionInfoSize := SizeOf(TOSVersionInfo) ;

   if GetVersionEx(osVerInfo) then

   begin

     minorVersion := osVerInfo.dwMinorVersion;

     majorVersion := osVerInfo.dwMajorVersion;

     case osVerInfo.dwPlatformId of

       VER_PLATFORM_WIN32_NT:

       begin

         if majorVersion <= 4 then

           Result := wvWinNT

         else if (majorVersion = 5) and (minorVersion = 0) then

           Result := wvWin2000

         else if (majorVersion = 5) and (minorVersion = 1) then

           Result := wvWinXP

         else if (majorVersion = 6) then

           Result := wvWinVista;

       end;

       VER_PLATFORM_WIN32_WINDOWS:

       begin

         if (majorVersion = 4) and (minorVersion = 0) then

           Result := wvWin95

         else if (majorVersion = 4) and (minorVersion = 10) then

         begin

           if osVerInfo.szCSDVersion[1] = 'A' then

             Result := wvWin98SE

           else

             Result := wvWin98;

         end

         else if (majorVersion = 4) and (minorVersion = 90) then

           Result := wvWinME

         else

           Result := wvUnknown;

       end;

     end;

   end;

end;

~~~~~~~~~~~~~~~~~~~~~~~~~

procedure TForm1.FormCreate(Sender: TObject) ;

var r : TRect;

begin

    //it would be good idea to move the

    //mouse inside the form before restriction

   r := BoundsRect;

   ClipCursor(@R) ;

end;

procedure TForm1.FormClick(Sender: TObject) ;

begin

   //always be sure to release the cursor

   ClipCursor(nil) ;

end;