This is the Bluefish HTML editor.

It has (among others) the following major features

  Customizable syntax highlighting
  Multiple encodings support
  Wizards for startup, tables, frames, and others
  Dialogs for many HTML tags, with all their attributes
  User-customizable toolbar for quick access to often used functions
  A snippets pane, specify your own tags or sets of code, and define your own dialogs
  Search and replace pattern support 
  Function reference browser, including reference files for PHP and HTML
  User customizable integration of many programs, including weblint, tidy, make

Installation:
  
  See INSTALL file for information on how to install Bluefish
  
Starting Bluefish:
  
  run from the command line: `bluefish'
  run `bluefish -h' for more startup options

  Several features are only available if you install some other programs too.
  This is necessary for the browser preview, checkers like weblint or tidy, ...

More information:
  
  http://bluefish.openoffice.nl/

Written by:
  
  see AUTHORS for more information

Reporting Bugs:
  
  Please report bugs to our bugtracker:
    https://sourceforge.net/p/bluefish/tickets/

  Include in the report:
    - version of Bluefish you are using
    - version of GTK you are using
    - a backtrace in case of a crash/segmentation fault

Contacting us:
  
  http://bluefish.openoffice.nl (homepage)
  https://sourceforge.net/projects/bluefish/lists/bluefish-community (mailinglist)