These are classes that handle a specific part of the editor, 
for example - the scintilla text editor, the bookmark/file browser or the class browser, each of the modules works independently of the other modules.

To communicate between modules, they must ask the module manager to broadcast or broadcast_get information from the other available modules. Normally when this communication is document specific, you would also send the bookmark id and document URL.

For more infomation, read about the module manager and the documents below that describe the specific modules.