Nationalist edit-warring 

The language of the Kingdom of Yugoslavia was Serbo-Croatian or "Serbo-Croato-Slovene", both alphabets were in use throughout (actually primarily Cyrillic). Present sources confirming that the Banovina of Croatia (which housed a very large Serbian population) is an exception, or stop vandalizing the article.

Using the civil flag as opposed to the state flag (per standard usage, and per the Kingdom of Yugoslavia article among others). Sources are very abundant regarding that flag being the civil flag.  (TALK)