Geany

Geany is a powerful and lightweight programmer's text editor.

Open HTML File in Firefox

Menu Build → Set Build Commands → Execute Commands:

Execute: firefox %d/%f

Configure Build Menu - Geany Wiki

Custom Commands (Linux)

Menu Edit → Format → Send Selection to → Set Custom Commands

Command: sort
Label: Sort lines

Command: tr [:upper:] [:lower:]
Label: To lower case

Command: tr [:lower:] [:upper:]
Label: To upper case

Sessions

You can start several instances of Geany, but only the first will load files from the last session [Manual]. To open selected files in a new instance of geany (-i) like in a new "session":

$ geany -i file1 file2 file3

Storing and opening session files can be done on a project basis. Project Organizer is an extension of Geany's project management displaying a tree of files belonging to the project in the sidebar.

More Info