Sorry for beign a bit rude with the replies. It is a common question and I am a bit annoyed that all my hard work on WebKit and WebPositive only results in “why don’t you use this or that other browser?”
No, it is specific to Haiku and uses APIs and libraries that are only available on Haiku.
This is the reason we decided to use the WebKit engine and not one of the others: it allows us to provide a browser that integrates very well with the system, for example, it uses the exact same font rendering as native applications.
In the future it will be possible to write parts of an application in C++ and parts in HTML/CSS and have the different part of the user interface seamlessly blend together. However we are not quite there yet