3.4 The Break gesture
The keyboard Break gesture is
This chooses a process that is useful to break, and breaks it.
The process to break is chosen as follows:
If the break gesture is sent to any LispWorks IDE window or other CAPI interface that is waiting for events, it does "Interface break", as described below.
Otherwise it checks for a busy processes that is essential for LispWorks to work correctly, or that interacts with the user (normally that means that some CAPI interface uses it), or that is flagged as wanting interrupts (currently that means a REPL). If it finds such a busy process, it breaks it.
Otherwise it activates or starts the Process Browser. Note that this tool, documented in The Process Browser, can be used to break any other process.
"Interface break" depends on the interface. For an interface that has another process, notably the Listener with its REPL, it breaks that other process. For most tools it starts the Process Browser, otherwise just it breaks the interface's process.
LispWorks IDE User Guide (Windows version) - 13 Sep 2017