Porting an open source project is quite different from developing a new application for mobile phones. During past days without Open C, we have to rewrite lots of code to satisfy both Symbian OS rules/limitation and difference between mobile devices and desktop computers. Touching so much code will cost more development time, but what's worse is that making changes too much will drive you thinking "Should I start a new project rather than using only a little from this existing project?". So porting an existing application onto Symbian OS makes you keep concerning how much modification will you make, if too much consider starting a new one or just share the name or brand. As far as I know, HelixCommunity is the first big and famous open source project ported to Symbian OS, and it supports as early as v6.1. I checked out its source in 2004 (means their code nowadays might be different a lot), this is one example of making too much changes so you can tell few difference between porting like this or making a new project. Since S60 3rd Edition, there is Open C we can utilize, the job is easier. But still we can not ignore this consideration because of the nature of mobile phones. In one word, first step of porting an existing project is evaluate how much changes will be made approximately.

This document in Forum Nokia web site is very helpful, and generally speaking smaller projects are always easier to make decision if it could be ported than bigger ones. Smaller ones are always based on some existing framework, if the framework exists or can be ported on Symbian OS then the project itself will be fine in most cases. Huge project like Mozilla or Helix will give us an impression that it is likely impossible to port cause it has so many dependencies and self owned framework. However, we want eveidence to support our decision. Let's get back to Mozilla, after searching its website, there is an "C/C++ Portability Guide" which shows us an amazing likeness of Symbian OS programming limitations. From this article, we could learn Mozilla code will probably contain very little exceptions, RTTI and others that Symbian OS C++ does not support. Then with the help of Open C, we could have better confidence about porting without changing too much code.

Next we have to  make  deeper  research on the inner  structure  of Mozilla platform, cause you can not start portting any piece of code without knowing which level it lies in and what it does actually. Stay tuned, I will bring more as the work goes on