Can you write a script which creates a new named group and 
adds all currently selected elements to it. 

from MSPyBentley import *
from MSPyECObjects import *
from MSPyBentleyGeom import *
from MSPyDgnPlatform import *
from MSPyDgnView import *
from MSPyMstnPlatform import *

import tkinter as tk
from tkinter import simpledialog, messagebox

def create_named_group_from_selection(group_name="MyNamedGroup"):
    """
    Creates a named group in the active DGN model and adds all currently selected elements to it.

    :param group_name: The name of the named group to create.
    :type group_name: str

    :returns: True if the named group is successfully created and elements are added, False otherwise.
    :rtype: bool
    """
    ACTIVEMODEL = ISessionMgr.ActiveDgnModelRef
    if ACTIVEMODEL is None:
        messagebox.showerror("Error", "No active DGN model.")
        return False

    namedGroups = NamedGroupCollection(ACTIVEMODEL)
    if namedGroups is None:
        messagebox.showerror("Error", "Could not get NamedGroupCollection.")
        return False

    # Create named group
    flag = NamedGroupFlags()
    ret = NamedGroup.Create(group_name, "", flag, ACTIVEMODEL)
    if BentleyStatus.eSUCCESS != ret[0]:
        messagebox.showerror("Error", f"Failed to create named group: {group_name}")
        return False

    group = ret[1]

    # Get the selected elements
    selSetManager = SelectionSetManager.GetManager()
    agenda = ElementAgenda()
    selSetManager.BuildAgenda(agenda)

    if agenda.GetCount() == 0:
        messagebox.showinfo("Info", "No elements selected.")
        return False

    # Add each selected element to the named group
    memberFlag = NamedGroupMemberFlags()
    for i in range(agenda.GetCount()):
        editElementHandle = agenda.GetEntry(i)
        if BentleyStatus.eSUCCESS != group.AddMember(editElementHandle.GetElementId(), ACTIVEMODEL, 
                                                     memberFlag):
            messagebox.showerror("Error", "Failed to add an element to the named group.")
            return False

    if BentleyStatus.eSUCCESS != group.WriteToFile(True):
        messagebox.showerror("Error", "Failed to write named group to file.")
        return False

    messagebox.showinfo("Success", f"Named group '{group_name}' created and elements added.")
    return True


def main():
    # Prompt user for group name using tkinter
    root = tk.Tk()
    root.withdraw()
    group_name = simpledialog.askstring("Named Group", "Enter name for the new Named Group:", 
                                        initialvalue="MyNamedGroup")
    if group_name:
        create_named_group_from_selection(group_name)
    else:
        messagebox.showinfo("Cancelled", "Operation cancelled by user.")


if __name__ == "__main__":
    main()