FlashDevelop extensions are regular *.zip archive files using *.fdz file extension. FlashDevelop extracts the contents of the archives using additional builtin arguments to extract the contents to the desired locations. You can create these extensions with normal ZIP archive tools. You just need to change the file extension to *.fdz when done.
See http://www.flashdevelop.org/wikidocs/index.php?title=Arguments for a full list of supported arguments.
FlashDevelop checks if any of the files being installed is an update to an already existing and possible locked (by FlashDevelop) binary file (*.fdl, *.fdb or *.dll) and if so, will request the user to restart FlashDevelop to update these files.
Syntax coloring extensions should use a word "theme" (in any case) in the filename to tell FlashDevelop to reload and refresh the code editor coloring configuration when the extension has been installed. Also the syntax coloring is now fully dynamic and no other *.xml files (like backups) should be in the Languages directory as they may override the other defined language and syntax coloring settings.
Here are few files demonstating the basic functionality of the extensions. Extract the files as a zip to see the structure of the files inside.
Default full theme for FD 4.3:
Trace plugin installer for FD 4.x:
Azoth tool and template installer for FD 4.x: