Trouble getting windowmanager properties to save it's contents with blend file I'd like the contents of this custom editor panel to persist with the file.

I can't seem to get my PropertyGroup or even a StringProperty to save with the blend file. 

class PG_mypg(bpy.types.PropertyGroup):
    custString = bpy.props.StringProperty(name="custString")

bpy.utils.register_class(PG_mypg)

# this adds it but it doesn't persist in the file
bpy.types.WindowManager.myPanelSettings = bpy.props.PointerProperty(type=PG_mypg)

# even this one doesn't save either
bpy.types.WindowManager.myCustString = bpy.props.StringProperty(name="customString")


Note that I want this to be set for my window, not per object.
Custom properties to the bpy.types.WindowManager type don't serialize to .blend
(as if options={'SKIP_SAVE'} was set).

Your options are to use


bpy.types.Scene, but you will need to chose one scene instance to store the actual properties, and if that scene is deleted, they will be gone
Serialization: serialize your data to a string and make it the text body of a new text datablock. Give the datablock a name that starts with a dot, e.g. .my-data, to hide it in the interface. It is less likely to be removed like a scene this way.
AddonPreferences or saving to a custom configuration file - if the data is relevant to not just the current .blend, but the local Blender installation