Xul Runner: does it require installed version of Firefox on the OS?
or does it compile its own web engine?
The dependancies are unclear to me, even when looking at their documentation.
Perhaps let me be clearer: The XULrunner can compile using firefox or you can compile without.
My question is this: If I were to create a XUL user interface, and use XULrunner, will the application created contain everything to display the user interface, or is it like .hta which requires IE. Hence my question: does firefox have to be installed on the target operating system?
No. XULRunner is an independent application, it has everything necessary to run XUL-based apps. This “everything necessary” is to a large part identical to what you find in Firefox but not entirely identical (some browser-specific things are missing). This also means that there is (at least) one catch: if you install XULRunner as part of your application you will also be responsible for updating it regularly – it has all the same security vulnerabilities as Firefox.