This Bugzilla instance is a read-only archive of historic NetBeans bug reports. To report a bug in NetBeans please follow the project's instructions for reporting issues.
Start NetBeans with about 15 projects open (some NB module projects). Select two, right click and choose "Close 2 Projects" from the popup menu. AWT thread is blocked for several minutes. See thread dump.
Created attachment 89337 [details] thread dump
Probably it should do similarly to Fix Imports when scanning is happening - provide a cancellable progress indication, but allow the user to do something else if cancelled.
BTW Fix imports does nothing when scanning is running, it just start another task, there is no cancelable dialog (at least for me).
*** This issue has been marked as a duplicate of 174253 ***