If I use "common" property types, such as QColor, QAlignment, or any kind of QFlag, everything works fine. Unfortunally, it seems that QEnums have issues with the python conversion, resulting in a "TypeError: unable to convert a C++ 'QVariant' instance to a Python object" in both PyQt4 and PyQt5. While Qt4 just seems to ignore the error, this results in a crash of Designer under Qt5.
As I can understand, there is no way to avoid this behavior, since the signal cannot be overloaded, and I sincerely doubt that this issue depends on the way I access the formEditor/propertyEditor.
Tested under PyQt 4.12 and 5.7.1.
È difficile avere una convinzione precisa quando si parla delle ragioni del cuore. - "Sostiene Pereira", Antonio Tabucchi http://www.jidesk.net