tkinter多选下拉列表

以下是一个使用tkinter实现多选下拉列表的例子：

import tkinter as tk
from tkinter import ttk

class MultiCombobox(ttk.Combobox):
    def __init__(self, master, values, **kw):
        self.values = values
        self.var = tk.StringVar()
        kw["textvariable"] = self.var
        ttk.Combobox.__init__(self, master, **kw)
        self.bind("<FocusIn>", self.popup)
        self.bind("<FocusOut>", self.unpost)
        self.listbox = None
        self.posted = False
        self.selection = []

    def popup(self, event):
        if not self.posted:
            self.listbox = tk.Listbox(self, height=len(self.values))
            self.listbox.configure(font=self.cget("font"),
                                   width=self.cget("width"))
            self.listbox.bind("<ButtonRelease-1>", self._select)
            self.listbox.bind("<Escape>", lambda event: self.unpost())
            self.listbox.place(in_=self, relx=0, rely=1)
            for value in self.values:
                self.listbox.insert("end", value)
            self.listbox.selection_clear(0, "end")
            for index in self.selection:
                self.listbox.selection_set(index)
            self.posted = True

    def unpost(self, event=None):
        if self.listbox:
            self.selection = self.listbox.curselection()
            self.var.set(", ".join([self.values[index] for index in self.selection]))
            self.listbox.destroy()
            self.listbox = None
            self.posted = False

    def _select(self, event):
        self.selection = self.listbox.curselection()
        self.var.set(", ".join([self.values[index] for index in self.selection]))
        self.listbox.destroy()
        self.listbox = None
        self.posted = False

if __name__ == "__main__":
    root = tk.Tk()
    values = ["选项1", "选项2", "选项3", "选项4", "选项5", "选项6"]
    cb = MultiCombobox(root, values=values, state="readonly")
    cb.pack()
    root.mainloop()