Make it easier to support complex properties for custom widgets written in Python.
It is relatively straightforward to create new widgets in Python and load them into glade using a custom plugin catalog. However, it is not obvious how to support complex properties like lists of strings or tables of data with pre-defined columns.
For example if a custom widget has a property which should contain a list of strings, although a GParamBoxed property type with a value-type of GladeStringList will allow editing of the property within Glade, it won't be properly saved/restored from the .ui file, nor will the value be properly set to the Widget. Other widgets such as GtkComboBoxText accomplish this through Widget Adaptor overrides, specified in the catalog. It is not obvious how to do something similar in Python. It appears from http://unpythonic.blogspot.com/2007/03/custom-pygtk-widgets-in-glade3-part-2.html that this used to be possible. But the APIs described in that 12yr-old article do not exist anymore.
The Gladeui module available through python gobject introspection exposes a WidgetAdaptor class with the appropriate methods but it is not obvious how to use this from Python. I've tried creating an adaptor subclass for corresponding widget and setting it using the "adaptor" attribute of the glade-widget-class in the catalog to no avail. It appears to be ignored in the current version of glade.