Lobby in Browsers?

I am working on different browsers from last few months. As per my experience I have seen there is lobby in browsers. Most of the browsers are having same platform. Like

These all browsers are built on the same platform (Mozilla):

Firefox
Mozilla
Netscape
Flock
Omniweb
3B
Camino

These all browsers are built on the same platform (Internet Explorer):

All IE versions
AOL

Opera & Safari have used different platforms.

So as per my experience if you covered all four (IE, Firefox, Opera & Safari) browsers then you have most probably covered all browsers (not talking about mobile etc browsers).

But yes browser issues are depends on the operating system also :)