I am so sorry this pictures s not about Yogyakarta. But I think this is interesting mosque which I have found in Gajah Raya Street, Semarang City, Central Java.
The mosque is called "Mesjid Agung". There are few unique things you can find in this building. The giant umbrellas is same with Nabawi Mosque's umbrellas, only two same umbrella in the earth. About the tower, that have size 99 meters represent Asmaul Husna (Allah's Names).
In front of the umbrellas, there are 9 shower pond, represent 9 people who spreading moslem religion in Indonesia. Look the tower picture, you can see few piles. there are 25 piles make a half circle, represent 25 of moslem prophet.
Unique mosque...