Shared Libraries should be stored in a "swf\_shared_swf\" folder, relative to the location a swf file is launched from.  (normally relative to game.swf)

These shared libraries are accessed at run-time, NOT compile time,
 so this path must be available from the location where the SWF is run FROM,
  game.swf in almost every case

Since game.swf is the assumed launch-point, all other swf files are coded to look for shared libraries in "swf\_shared_swf\" relative to game.swf



For testing purposes, the game's "swf" folder also contains a symbolic link to another "swf\_shared_swf\" resulting in "swf\swf\_shared_swf\"
 allowing SWF files to be run from within the swf folder
 "swf\swf\_shared_swf\" is not needed for game.swf


Shared library movieClips loaded by other shared library movieclips won't load when tested within the Flash Editor if they are not places on FRAME 1
 So textbox.swf has window_bg on frame 1, so window_bg loads correctly in the Flash Editor.


WHY??
Shared movieClips
Easy importing when converting the game into a single self-contained SWF file.


HOW?
When importing for a self-contained file,
copy the movieClip to the game's library  (keep all additional folders that it copies with it), 
then double-click the movieClip to convert the shared-library movieClip into a local copy movieClip.
