sorry for stupid question ...I'm a newbie ... pauldstewart: "idiotto?" ... do you want to offend me? ..why? btw I have solved with these scripts:

//ClosePainting (GUI.texture script)

var windowOpen : boolean;
var windowRect : Rect = Rect (20, 20, 450, 450);
var customSkin : GUISkin;
var aTexture : Texture;
var button : int;

// hide the window
function Start() {
    Hide(); 
}

// if I click the 3D object on the scene, the variable is true and...
 function Show(painting : Painting) {
  windowOpen = true;    
}

// ... set the custom skin, alpha, window rect and start WindowFunction
 function OnGUI () {
  GUI.skin = customSkin;
  GUI.color.a = 0.8;
  if (windowOpen) {
    windowRect = GUI.Window (5, windowRect, WindowFunction, "My Window");
  }
 }

// create a X button for close the window and drag the window with texture
function WindowFunction (windowID : int) {
    if (GUI.Button (Rect (0, 0,30, 30), "X")) {
    Hide();    
  }
  GUI.DrawTexture(Rect(0,0,400,400), aTexture, ScaleMode.ScaleToFit, false, 0f);
  GUI.DragWindow (Rect (0,0,430,430));
}

// hide function for close the window (boolean=false)
function Hide() {
    windowOpen = false; 
} 

and 3D object script:

function Update () {
}

private var closePainting : ClosePainting;

function Start () {
    closePainting = FindObjectOfType(ClosePainting);
}

function OnMouseDown () {
    closePainting.Show(this);
}

now I'm working on rotate and zoom the window and cursor change (from arrow to hand)..