Which GUI can have indefinite loop ?

[jst]

I am not going to click on that link.

Sounds like you want to periodically update displays to show information you get from MetaTrader. You probably want to use a thread to get the MetaTrader information. You don't want the GUI to be unresponsive while this happens. You'll also need a way for the MetaTrader thread to tell the application it is time to update displays. The MetaTrader thread cannot do this itself, so it will have to set a signal flag (semaphore) that the GUI will periodically check (using the .after() method).

Yes. But it's constantly not periodically. The GUI is for displaying the data from the loop. That's exactly what I was thinking too, using the thread for getting the data.

Can .after() be set in milisecond ? So it updates almost realtime, not delayed.