I didn't know appending that to the url would open a new window...
target="_blank" is the only way, Unless you want to use javascript, then anything is possible, however it is more complex.
It depends on the browser and options like you have all said here. Rejetto should not have to add this as a feature of hfs.
To be honest I used to target="_blank" a lot of links. But it decreases usability and can be annoying for users. A lot of people like to select for themselves. In Firefox it is the first option in the context menu of a link. It is best to keep most links within the same site opening in the same window. Some external links might be best as a new window, but I even find most people prefer external links opening in the same window, even if it does draw attention away from your own website.