I have the hp bars of mobs always turned on. You can do this through a default keybind (mine has been bound to a different key for so long I forget what the default is). You can also make friendly unit hp bars appear too, etc.

I MA alot. Having the mob hp bars up is very helpful for selecting targets. There is only one problem. The hp bars have a small range. Thankfully this range is beyond the deadzone, but not by much. Move beyond that, and the hp bars disappear. As a MM Hunter MA with Hawkeye, this is a little frustrating - I cant stand at maximum range and MA at 100% efficiency. The hp bars will show up if a mob is behind a wall, or player or the like, so they are very useful. Standing back at range and not having targets visible is a bad way to target.

So, I was wondering if there is a way to extend the range at which the hp bars can be seen. For example, by modifying something in the config file (the same way you can change the range values for which data for the combatlog is gathered). Any ideas?

This came up in the official UI forums recently. Last I checked, no one had figured out a way to do it yet.