thank you d_stranz, to be honest i was thinking if it is possible if i can assign different symbols to different points in a curve and in that i can subclass the QwtSymbol and have the Id with each point "symbol" i draw.

or the other option i was think of each point would be a curve that has only one point!!!! but i really feel it is really bad idea especially that i would have to draw lots of points that may reach hundred thousands.

the closest point, I'm not sure how well this would work as i have the points will be pretty close to each other.
Please inform me if one of these approaches is possible or there are very bad idea.

I have just saw the event_filter example in and it has an interactive plot and Symbols, ill be looking into it and see if i can under stand the approach and apply it on my case .

Thank you so much