You can compile plugins within ImageJ using with either the Plugins->Compile 
and Run command or using the File->Compile and Run command in ImageJ's built 
in editor (Plugins->Edit).

The four QuickTime plugins are preinstalled in the Import and Save As
submenus.

The QuitHandler plugin in the Utilities folder is called by ImageJ to 
process the "About" and "Quit" commands in the Apple menu and to open 
files dropped on ImageJ and files with creator code "imgJ" that are double-clicked.