medit is a programming and around-programming text editor.
Started originally as a simple built-in editor component in GGAP, it grew up to a real text editor.
Configurable syntax highlighting.
Configurable keyboard accelerators.
Multiplatform - works on unix and windows.
Plugins: can be written in C, Python, or Lua.
Configurable tools available from the main and context menus. They can be written in Python or Lua, or it can be a shell script.
Regular expression search/replace, grep frontend, builtin file selector, etc.
Sourceforge project page: http://sourceforge.net/projects/mooedit/