Basically you can say what you like as long as you don't start influencing policy in any effective way. if there's any danger of that media time is denied and you can continue muttering angrily to yourself as if it makes a difference, as we do here.

But start damaging property and destroying the wealth of important people and you'll soon discover the limits of what's allowed.

Off course...
During Milosevic at first he would allow "demonstrations of support" to him and his policy but he did not feel that he needs to let opposition same right to demonstrate. As we all know he even tried to use force to disperse protests but it did not work. Later, he would let us protest (simply he did not have a chance to stop us) to the extent of letting us vent our anger. He has learned that eventually we will get tired and go home. Every time we were allowed to march streets of Belgrade and to scream in front of different institution and every time our task was to enter TV Serbia building and that's where every time we were stoped with huge force. Once they marched to Milosevic's residency in Belgrade and of course when they came close enough they were met with force. We used slogans like" Slobo - Sadame" meaning" Milosevic = Saddam" and Saddam at the time was doing well and was alive and we all knew him as a ruthless dictator. But we did not use bad language. Just to illustrate things a bit...  

Science without religion is lame, religion without science is blind...Albert Einstein