And you were there - that's why I'm asking you.
What I hear you saying is that if a church falls into their hands by legitimate means then it is OK for it to be turned into a mosque. (As you may know, the largest mosque in Istanbul was once a Christian church.)
But, you have first hand knowledge -- I've never been there: Have any Christian churhces in what was Yugoslavia been destroyed since that nation broke up? If so, how many?
Well, ben, you brought it up and didn't attribute it to anyone else--what else was I supposed to think? If you're asking me did I ever see or hear of mosques being built on top of Christian churches over there, the answer is no--as I described before, it would have been virtually impossible to do. However, when the Ottomans were in charge in the Balkans area, such things certainly did occur.
What I hear you saying is that if a church falls into their hands by legitimate means then it is OK for it to be turned into a mosque.
"legitimate" is the key word here. Its someone's property to do with as they see fit--whether you or I like it or not.
Have any Christian churhces in what was Yugoslavia been destroyed since that nation broke up? If so, how many?
A lot. However, it is an inconvenient fact for the world-view of many that the Christians in the Balkans have actually destroyed far more Christian Churches than the Muslims. You can follow the links here and read about Serbs destroying hundreds of Catholic Churches with a description of individual churches & monasteries, etc. The Catholic Croats seem to be in second place as they are listed as destroying hundreds of Serb churches & religious sites--you can read about that in this Orthodox Church report; although the Bosniak Muslims certainly contributed as well.
In Kosovo, where all the publicity is focused, although the Albanians are Johnny-come-latelies to the church destruction business as compared to their Slavic neighbors, they have chipped in as an international religious freedom group reports:
Although more than 100 [Orthodox Churches]have been damaged or destroyed since the international community took control in 1999, Forum 18 has found no evidence that anyone has been prosecuted for these attacks (just as no-one is known to have been prosecuted for Serbian paramilitary and army attacks on 215 mosques during the 1999 war). This pre-dates the March 2004 riots so another 30 should be added to the total; attacked by the Kosovo Albanians. Bishop Sopi of the Catholic Diocese of Prizren complained after the 1999 war that Serb troops occupied, damaged and looted some of his Catholic Churches, so there's a few more Christian Churches to add in.
In the Bosnian Federation Republika Srpska, the 2004 U.S. State Department Religious Freedom report says "In early post-war years, RS authorities frequently did not intervene to prevent the violent obstruction of efforts to rebuild some of the 618 mosques and 129 churches in the RS that were destroyed or significantly damaged during the 1992-1995 war." so there's some more numbers to consider.
Of course, as you can see from the above, there are also hundreds of mosques destroyed, so everybody took their hits. All in all, the Serbs clearly outperformed the other national groups in Yugoslavia in terms of dealing out destruction to both churches and mosques, but then they are the biggest group and controlled most of the military when Yugoslavia broke up.
The Patriarch of the Serb Orthodox Church sums it up pretty well: " ... so much evil has happened, even amongst ourselves. With the same sadness, and shame, we hear about the destruction of Roman Catholic churches and Muslim mosques. Our heads bowed in sorrow, we pray to God that these troubles will finally end, never again to be repeated anywhere in the world, and never again to befall any nation.