It seems that the "highlight matching delimiters" feature does not work correctly when a line contains real tab characters rather than spaces. I will work on fixing this. In the meantime, you should be able to turn off this feature and then you won't have the problem with fantom delimiters being drawn over the real content. These are drawing glitches and the actual source code is not affected, btw.
In addition to fixing it, could you add functionality to automatically convert the tab character into spaces (like when you press the tab key)? That way I could paste in someone else's code, which uses tabs, and have them become spaces automatically.
I'm all for gun control... that's why I use both hands when shooting
I have uploaded a new test release which fixes the delimiter highlighting bug and includes .h and .nxh file extensions as valid NXC code for the compiler. It also corrects a serious problem from the previous test release where all the pre-NXT communication code was not linked into the application, which broke support for the RCX, Scout, Spybot, and Cybermaster. This was due to a build error that occurred when I built the last test release.