Quote Originally Posted by 21did21 View Post
yes but i don't understand very well the content...

it's too difficult for me, i don't understand why qt don't work correctly for this applciation
Well, I'm sorry, I can't teach you to read with understanding. The docs for update() clearly state what your problem is. Your problem is very easy to solve but there is no point in giving you a ready solution if you wouldn't understand it. I can also point you to this article: [wiki]Keeping the GUI Responsive[/wiki] and suggest to take the "step by step" approach.

a friend use C++ builder and it can do this easily, so why i can't with Qwt?
Because Qt is event-driven and the other framework is not. Thanks to that Qt is fast and your friend's framework is not.

i think it's easy command but i don't find the correct command and i don't understand where i have to put tjis command....
What command?