How to use core.thread.Thread

[aki via Digitalmars-d-learn]

I can't resolve the compile errors:

import core.thread;
class DerivedThread : Thread {
        int count = 0;
        this() {
                super(&run);
        }
        private void run() {
		inc();	//testThread.d(8): Error: shared method 
testThread.DerivedThread.inc is not callable using a non-shared 
object
        }
        synchronized void inc() {
		++count;	//testThread.d(11): Deprecation: read-modify-write 
operations are not allowed for shared variables. Use 
core.atomic.atomicOp!"+="(this.count, 1) instead.
        }
}
void main() {
        auto thr = new DerivedThread();
        thr.start();
	thr.inc();	//testThread.d(17): Error: shared method 
testThread.DerivedThread.inc is not callable using a non-shared 
object
        thr.join();
}

1. Should I declare thr as shared? But
        auto thr = new shared DerivedThread();
does not resolve it.

2. Why "++count" cause an error? I think it is safe because
it is marked as synchronized. If it is forced to use atomicOp
all the time, it's painful.

3. Are there any tutorials about using Thread class?

Aki.