What's the relationship between signal/slot and event?

[Dusdan]

I have several questions:
1).Signal/slot mechanism is synchronous or not? If it is,that means we should not let a slot do much work,otherwise the UI will be blocked for much time.
2).QEvent is asynchronous or not? For example ,if I call the update() function,the paintEvent() will be called, if it is asychronous,the UI will not be blocked.
3).Is there any relationship between signal/slot and event? Does Qt put the slots into event queue?
4).Qt document says that main event loop fetches native window system events and sends the translated events to QObjects,I want to know what's the relationship between main event loop and QWSServer?

Thanks!

1) it depends, you can call a slot in both synchronous and asynchronous mode;
2) same as before, it depends if you use sendEvent or postEvent. update is asynchronous
3) don't know exactly, I think there are two different queues for slots and events, but i'm not sure, I have to check the code.
4) I don't know, sorry