exec sys.UTL_RECOMP.RECOMP_PARALLEL( 8);
It runs for a while, so click [Cancel]. All seems OK, till you try to run anything.
Option 1: try to run any query - TOAD freezes (the window goes white/greyed out).
Option 2: click "Terminate" button on the toolbar - TOAD freezes.
The freeze is not infinite. TOAD comes back to the living when the long running task finishes.
But what if you have PL/SQL that runs an infinite loop that you want to terminate?