2 Answers

• You could use as a "loading screen" a window that is set fullscreen ( and maybe modal ).

• I use the following code, which can disable the whole screen with a transparent full screen window:

  /**
   * Disable the screen
   */
  var screenHideWin = null;
  var disableScreen = function(e) {
      screenHideWin = Ti.UI.createWindow();
      screenHideWin.open({fullscreen:true});
  };
  Ti.App.addEventListener('disableScreen', disableScreen);
  
  /**
   * Reenable disabled screen
   */
  var enableScreen = function(e) {
      screenHideWin.close();
      screenHideWin = null;
  };
  Ti.App.addEventListener('enableScreen', enableScreen);
  

  You can call the functions directly or by an event:

  Ti.App.fireEvent('disableScreen');
  //...
  Ti.App.fireEvent('enableScreen');