How to properly implement tkMessageBox in Python3.4?
Question: I want to launch a warning using tkMessageBox in Python3. This warning is
supposed to launch when a user doesn't select an element from a listbox.
Unfortunately whenever I try to implement message box it does not launch like
it is supposed to. I have code for a script called pietalkgui.py which
contains the code where I want to implement the message box:

    
    
    from tkinter import messagebox
    
    # Gives warning if no user is selected for whisper
    def whisperwarning(self):
        # show warning to user
        showwarning("Select User","Select a user to whisper to!")
    
    # Handles whisper
    def whispermessage(self):
        # stores element selected in temp variable
        temp = self.userslist.get(self.userslist.curselection())
         # if no item is selected from userslist (listbox)
        if temp == "":
            # launch warning to user if no item is selected
            self.whisperwarning()
        else:
            # retrieves usernames from userslist
            username = temp
            # storing whisper
            outwhisper = ' /w "' + username +'" ' + self.messagebox.get("0.0",END)
            # handling whisper
            self.handler(outwhisper)
            # erase message in message box
            self.messagebox.delete("0.0",END)
    

Am I doing something wrong in the implementation of tkMessageBox? Or am I not
properly checking if not item is selected from the listbox?


Answer: It appears that you are calling the method `showwarning`, but haven't defined
it or imported it. That is the name of a function the `messagebox` module, so
perhaps you need to change this:

    
    
    showwarning("Select User","Select a user to whisper to!")
    

... to this:

    
    
    messagebox.showwarning("Select User","Select a user to whisper to!")
    

Also, FWIW, this code is slightly incorrect:
`self.messagebox.delete("0.0",END)` \-- text indices start at "1.0", not
"0.0".

