Attachment to classes derived from CTkComboBox or CTkOptionMenu does not work properly

[nexperion]

I am using classes derived from CTkComboBox and CTkOptionMenu as comboboxes and option menus. Attaching CTkScrollableDropdown to these derived classes does not work properly - the dropdown arrow does not open the dropdown, and the selected item is not returned to the combo box/option menu either.
This is because in the CTkScrollableDropdown constructor,

self.attach.winfo_name().startswith("!ctkcombobox")

is used to identify the class of 'attach', and that fails for derived classes. Why not using

isinstance(self.attach, customtkinter.CTkComboBox)

instead?