When executing a "Widget Node Command" core's GUI blocks waiting for the command to complete. This happens, for example, when trying to launch Wireshark as suggested in #811, leaving the core's GUI unusable until Wireshark is closed.

Steps to reproduce the behavior:

1. Add a new node command for wireshark
2. Right-click in a node and launch the corresponding wireshark node command
3. Core's GUI hangs

• CORE Version 9.1.0-2