I started working in a company that develop PLCs in the end of August 2009. We already have a working Ladder Diagram Editor, and I became responsible for the development. I want to port it to QT, today it is built with c++ builder 5 (its quite old, I know).

This version is very dificult to maintain, because it uses Canvas to draw everything. Every time the hole screen is redrawn, that's the hard part. I have to deal with every aspect of the action the user have done and everything is around that action.

So, I need some kind of widget, class, whatever, that might give me less trouble.
I will take a look at the sugestions you gave me this weekend.

I also need develop some code editor. I thought of QScinttila. Is it good?
Anybody has any other sugestion?