See ChangeLog for full details. It is written primarily in C and Tcl and serves to illustrate that Linux applications can indeed bridge to Windows. By design BrowseX is composed of numerous C widgets, each of which can be used independantly. Tcl glues everything together, the user has access to configure any widget, even form fields in web pages. The first comes really as a side effect of using Tcl for all highlevel algorithms.
Errors result in popup dialogs rather than crashes.
Responsiveness is probably due to lightweight and the widget based implementation forcing clean interfaces between the parts. Precompiled binaries are currently provided for Linux and Win32. There is also a unified build script for Linux, for rebuilding from scratch. Javascript is still not enabled. For the impatient, here is the Download page.