Fix a bug in monitor.py, which may stop the thread.
Fix a bug in monitor.py, which may stop the thread.

caodg/docklet,caodg/docklet,caodg/docklet,scorpionis/docklet,caodg/docklet,scorpionis/docklet,FirmlyReality/docklet,FirmlyReality/docklet,FirmlyReality/docklet,FirmlyReality/docklet