I've installed the Character Browser plug-in yesterday. Today I wondered why my project file has changed; I could not remember to have changed anything of the project configuration. Well, the Character Browser plug-in added its font setting to the project file. IMHO it is a common misconcept that a couple of plug-ins write their user-settings (aka machine or user dependent) to the project file. If some other user does not use this plug-in (finally it is not needed for project development) or prefer other fonts (or potential other platforms), conflicts are inherent.
The result is, that we move our project files to a "do not commit!" change set, which should not be the project file purpose.