operators.py

        if laycol_parent["ptr"].exclude:
            orig_parent_exclude = True

        if laycol_parent["ptr"].hide_viewport:
            orig_parent_hide_viewport = True

        laycol_parent["ptr"].collection.hide_select = False
        laycol_parent["ptr"].exclude = False
        laycol_parent["ptr"].hide_viewport = False


        # remove all hiding properties of this collection
        collection.hide_select = False
        laycol["ptr"].exclude = False
        laycol["ptr"].hide_viewport = False


        # shift all objects in this collection to the parent collection
        if collection.objects:
            orig_selected_objs = context.selected_objects
            orig_active_obj = context.active_object

            # select all objects in collection
            bpy.ops.object.select_same_collection(collection=collection.name)
            context.view_layer.objects.active = context.selected_objects[0]

            # remove any objects already in parent collection from selection
            for obj in context.selected_objects:
                if obj in laycol["parent"]["ptr"].collection.objects.values():
                    obj.select_set(False)

            # link selected objects to parent collection
            bpy.ops.object.link_to_collection(collection_index=laycol_parent["id"])

            # remove objects from collection
            bpy.ops.collection.objects_remove(collection=collection.name)

            # reset selection original values
            bpy.ops.object.select_all(action='DESELECT')

            for obj in orig_selected_objs:
                obj.select_set(True)
            context.view_layer.objects.active = orig_active_obj


        # shift all child collections to the parent collection
        if collection.children:
            for subcollection in collection.children:
                laycol_parent["ptr"].collection.children.link(subcollection)

        # reset hiding properties of parent collection
        laycol_parent["ptr"].collection.hide_select = orig_parent_hide_select
        laycol_parent["ptr"].exclude = orig_parent_exclude
        laycol_parent["ptr"].hide_viewport = orig_parent_hide_viewport


        # remove collection and update tree view
        bpy.data.collections.remove(collection)


        update_property_group(context)

        if len(context.scene.CMListCollection) == context.scene.CMListIndex:
            context.scene.CMListIndex = len(context.scene.CMListCollection) - 1
            update_property_group(context)


        # reset history
        for rto in rto_history.values():
            rto.clear()

        return {'FINISHED'}

rename = [False]
class CMNewCollectionOperator(bpy.types.Operator):
    '''Add New Collection'''
    bl_label = "Add New Collection"
    bl_idname = "view3d.add_collection"
    bl_options = {'UNDO'}

    child: BoolProperty()

    def execute(self, context):
        global rto_history

        new_collection = bpy.data.collections.new('Collection')
        scn = context.scene

        # if there are collections
        if len(scn.CMListCollection) > 0:
            # get selected collection
            laycol = layer_collections[scn.CMListCollection[scn.CMListIndex].name]

            # add new collection
            if self.child:
                laycol["ptr"].collection.children.link(new_collection)
                expanded.append(laycol["name"])

                # update tree view property
                update_property_group(context)

                scn.CMListIndex = layer_collections[new_collection.name]["row_index"]

            else:
                laycol["parent"]["ptr"].collection.children.link(new_collection)

                # update tree view property
                update_property_group(context)

                scn.CMListIndex = layer_collections[new_collection.name]["row_index"]

        # if no collections add top level collection and select it
        else:
            scn.collection.children.link(new_collection)

            # update tree view property
            update_property_group(context)

            scn.CMListIndex = 0

        global rename
        rename[0] = True

        # reset history
        for rto in rto_history.values():
            rto.clear()

        return {'FINISHED'}


phantom_history = {"view_layer": "",
                   "initial_state": {},

                   "exclude_history": [],
                   "select_history": [],
                   "hide_history": [],
                   "disable_history": [],
                   "render_history": [],

                   "exclude_all_history": [],
                   "select_all_history": [],
                   "hide_all_history": [],
                   "disable_all_history": [],
                   "render_all_history": []
                   }

class CMPhantomModeOperator(bpy.types.Operator):
    '''Toggle Phantom Mode'''
    bl_label = "Toggle Phantom Mode"
    bl_idname = "view3d.toggle_phantom_mode"

    def execute(self, context):
        global phantom_history
        global rto_history

        scn = context.scene
        view_layer = context.view_layer.name

        # enter Phantom Mode
        if not scn.CM_Phantom_Mode:

            scn.CM_Phantom_Mode = True

            # save current visibility state
            phantom_history["view_layer"] = view_layer

            laycol_iter_list = [context.view_layer.layer_collection.children]
            while len(laycol_iter_list) > 0:
                new_laycol_iter_list = []
                for laycol_iter in laycol_iter_list:
                    for layer_collection in laycol_iter:
                        phantom_history["initial_state"][layer_collection.name] = {
                            "exclude": layer_collection.exclude,
                            "select": layer_collection.collection.hide_select,
                            "hide": layer_collection.hide_viewport,
                            "disable": layer_collection.collection.hide_viewport,
                            "render": layer_collection.collection.hide_render,
                                }

                        if len(layer_collection.children) > 0:
                            new_laycol_iter_list.append(layer_collection.children)

                laycol_iter_list = new_laycol_iter_list


            # save current rto history
            for rto, history, in rto_history.items():
                phantom_history[rto+"_history"] = history.get(view_layer, {}).copy()


        # return to normal mode
        else:
            laycol_iter_list = [context.view_layer.layer_collection.children]
            while len(laycol_iter_list) > 0:
                new_laycol_iter_list = []
                for laycol_iter in laycol_iter_list:
                    for layer_collection in laycol_iter:
                        phantom_laycol = phantom_history["initial_state"][layer_collection.name]

                        layer_collection.exclude = \
                            phantom_laycol["exclude"]

                        layer_collection.collection.hide_select = \
                            phantom_laycol["select"]

                        layer_collection.hide_viewport = \
                            phantom_laycol["hide"]

                        layer_collection.collection.hide_viewport = \
                            phantom_laycol["disable"]

                        layer_collection.collection.hide_render = \
                            phantom_laycol["render"]


                        if len(layer_collection.children) > 0:
                            new_laycol_iter_list.append(layer_collection.children)

                laycol_iter_list = new_laycol_iter_list


            # restore previous rto history
            for rto, history, in rto_history.items():
                history[view_layer] = phantom_history[rto+"_history"].copy()

            scn.CM_Phantom_Mode = False


        return {'FINISHED'}