I know Nautilus has support for Mercurial, but I'm not seeing the icon overlays even after installing tortoisehg-nautilus on Ubuntu 14.04.
I'm interested in knowing which Linux file explorers (both GUI and terminal curses) have support for Mercurial?
That is, if I look at the files and directories in the file explorer, I should be able to quickly see which of them are not in the repository, which are modified and which are up to date.
Kate editor has a plugin that supports mercurial git and subversion. I did not try it personally with mercurial but I guess it should work if they say it supports it.
You can search your self for more editors, here is a list with some text editors: