I read it as the animation, I'm sure Marcos will let us know.
        
        
     
Thanks 
@stevel05  and 
@Erel .
@Erel is correct. 
@stevel05 Yesterday I read your answer in my mobile phone and hadn't chance to test up to now. The solution presented by 
@stevel05 does some of the behaviors those I need, but not all:
- When x is clicked, the program isn't stopped because the event is consumed (EventData.Consume - great! I didn't know this resource in B4J) BUT
- The window is minimized (not hidden) and I still need the system tray icon
 
   Remember also that I'm using B4XViews which could request some modification in the commands... (_CloseRequest (EventData As Event) - what's the "form" name in B4XViews program?)... must to check...
   Then, I think that the complete solution will be using jSystemTray like 
@Erel mentioned (which probably will consume the "close" event also as 
@stevel05 used in his code). I'll check jSystemTray, test and update here! Thanks !!!