For those who develop ChimeraX plugins with graphical user interfaces, today we switched ChimeraX from using PyQt5 to using PySide2. These are nearly identical Python interfaces to the Qt window toolkit. In your code you will probably only need to change imports of PyQt5 to instead import PySide2. There are a few other small differences (e.g. pyqtSignal becomes Signal, and QAction callbacks may not have the same arguments) and more details about the differences are in this ChimeraX ticket <https://plato.cgl.ucsf.edu/trac/ChimeraX/ticket/1635#comment:34>https://plato.cgl.ucsf.edu/trac/ChimeraX/ticket/1635 <https://plato.cgl.ucsf.edu/trac/ChimeraX/ticket/1635> We made the switch because PySide2 has a bigger community development team, part of the Qt project, and has less restrictive licensing. Tom