cannot edit html files

[fossildoc]

I know this is my fault, but I just can't find it.

Both in version 5 and 6, I am unable to edit html files. I cannot select anything, so of course cut and paste won't work.

I have checked the file options for html files; they are identical to those for txt files. There doesn't seem to be any option that differs between the two file types. There's nothing wrong with the file, either; if I change the file extension from .html to .txt, everything works fine.

Since nobody else has complained about this, it must be something really simple that I'm missing. Any help, please.