curve_assign_shapekey.py

    alignList : EnumProperty(name="Vertex Alignment", items = \
        [("-None-", 'Manual Alignment', "Align curve segments based on starting vertex"), \
         ('vertCo', 'Vertex Coordinates', 'Align curve segments based on vertex coordinates')], \
        description = 'Start aligning the vertices of target and shape keys from',
        default = '-None-')

    alignVal1 : EnumProperty(name="Value 1",
        items = matchList, default = 'minX', description='First align criterion')

    alignVal2 : EnumProperty(name="Value 2",
        items = matchList, default = 'maxY', description='Second align criterion')

    alignVal3 : EnumProperty(name="Value 3",
        items = matchList, default = 'minZ', description='Third align criterion')

    matchParts : EnumProperty(name="Match Parts", items = \
        [("-None-", 'None', "Don't match parts"), \
        ('default', 'Default', 'Use part (spline) order as in curve'), \
        ('custom', 'Custom', 'Use one of the custom criteria for part matching')], \
        description='Match disconnected parts', default = 'default')

    matchCri1 : EnumProperty(name="Value 1",
        items = matchList, default = 'minX', description='First match criterion')

    matchCri2 : EnumProperty(name="Value 2",
        items = matchList, default = 'maxY', description='Second match criterion')

    matchCri3 : EnumProperty(name="Value 3",
        items = matchList, default = 'minZ', description='Third match criterion')

    markVertex : BoolProperty(name="Mark Starting Vertices", \
        description='Mark first vertices in all splines of selected curves', \
            default = False, update = markVertHandler)


class AssignShapeKeysPanel(Panel):

    bl_label = "Assign Shape Keys"
    bl_idname = "CURVE_PT_assign_shape_keys"
    bl_space_type = 'VIEW_3D'
    bl_region_type = 'UI'
    bl_category = "Edit"

    @classmethod
    def poll(cls, context):
        return context.mode in {'OBJECT', 'EDIT_CURVE'}

    def draw(self, context):

        layout = self.layout
        col = layout.column()
        params = context.window_manager.AssignShapeKeyParams

        if(context.mode  == 'OBJECT'):
            row = col.row()
            row.prop(params, "removeOriginal")

            row = col.row()
            row.prop(params, "space")

            row = col.row()
            row.prop(params, "alignList")

            if(params.alignList == 'vertCo'):
                row = col.row()
                row.prop(params, "alignVal1")
                row.prop(params, "alignVal2")
                row.prop(params, "alignVal3")

            row = col.row()
            row.prop(params, "matchParts")

            if(params.matchParts == 'custom'):
                row = col.row()
                row.prop(params, "matchCri1")
                row.prop(params, "matchCri2")
                row.prop(params, "matchCri3")

            row = col.row()
            row.operator("object.assign_shape_keys")
        else:
            col.prop(params, "markVertex", \
                toggle = True)


def updatePanel(self, context):
    try:
        panel = AssignShapeKeysPanel
        if "bl_rna" in panel.__dict__:
            bpy.utils.unregister_class(panel)

        panel.bl_category = context.preferences.addons[__name__].preferences.category
        bpy.utils.register_class(panel)

    except Exception as e:
        print("Assign Shape Keys: Updating Panel locations has failed", e)

class AssignShapeKeysPreferences(AddonPreferences):
    bl_idname = __name__

    category: StringProperty(
            name = "Tab Category",
            description = "Choose a name for the category of the panel",
            default = "Edit",
            update = updatePanel
    )

    def draw(self, context):
        layout = self.layout
        row = layout.row()
        col = row.column()
        col.label(text="Tab Category:")
        col.prop(self, "category", text="")

# registering and menu integration
def register():
    bpy.utils.register_class(AssignShapeKeysPanel)
    bpy.utils.register_class(AssignShapeKeysOp)
    bpy.utils.register_class(AssignShapeKeyParams)
    bpy.types.WindowManager.AssignShapeKeyParams = \
        bpy.props.PointerProperty(type=AssignShapeKeyParams)
    bpy.utils.register_class(ModalMarkSegStartOp)
    bpy.utils.register_class(AssignShapeKeysPreferences)
    updatePanel(None, bpy.context)

def unregister():
    bpy.utils.unregister_class(AssignShapeKeysOp)
    bpy.utils.unregister_class(AssignShapeKeysPanel)
    del bpy.types.WindowManager.AssignShapeKeyParams
    bpy.utils.unregister_class(AssignShapeKeyParams)
    bpy.utils.unregister_class(ModalMarkSegStartOp)
    bpy.utils.unregister_class(AssignShapeKeysPreferences)

if __name__ == "__main__":
    register()