In 3.6 via the all in one and threads views of the debugger, it used to be 
really easy to find deadlocks. By selecting a waiting thread you could click 
on the object (monitor) it was waiting for, and then find out which threads 
were also waiting on the object and more importantly see which threads owned 
the monitor.

In 4.1 it seems the only way to find out which thread owns a monitor, is by 
manually clicking on each thread to find out if it owns the monitor. This is 
very laborious when an application has many (>50) threads.

I always impressed people with the way netbeans could find deadlocks in 3.6. 
To me it's a real shame this functionlity has gone.

I understand the debugger now operates differently (because the all in one 
display has gone), however perhaps a right click on an object monitor in the 
threads view could open a window listing the threads that own or are also 
waiting on the same monitor. Then instead of searching for the thread, the 
user can quickly open the right thread and find any deadlock.