How to change a entry widgets border color in Python Tkinter

Question

I am working on a program that has a entry widget. And when the user clicks a button and that entry widget is empty then the program will change the border color if it to red. But when I try the border just stays the same color. Which is black.

Here is the code:

self.timeField = Entry(self.mfr, width=40, relief=SOLID, highlightbackground="red", highlightcolor="red")
self.timeField.grid(row=0, column=1, sticky=W)

Then in the if statement that checks if it is empty has this to change it to red but it does not seem to work:

self.timeField.config(highlightbackground="red")
self.timeField.config(highlightcolor="red")

Can someone explain to me why this is not working, what I am doing wrong, and a way to fix it? Thanks in advance.

Update: Here is the rest of the code as requested:

def start(self):
    waitTime = self.timeField.get()
    password = self.passField.get()

    cTime = str(self.tVers.get())
    self.cTime = cTime

    if waitTime.strip() != "":
        if password.strip() != "":
            if waitTime.isdigit():
                if self.cTime == "Secs":
                    waitTime = int(waitTime)
                elif self.timeVer == "Mins":
                    waitTime = int(waitTime) * 60
                else:
                    waitTime = int(waitTime) * 3600

                self.password = password

                root.withdraw()
                time.sleep(float(waitTime))
                root.deiconify()
                root.overrideredirect(True)
                root.geometry("{0}x{1}+0+0".format(root.winfo_screenwidth(), root.winfo_screenheight()))

                self.tfr.destroy()
                self.mfr.destroy()
                self.bfr.destroy()

                self.create_lockScreen()
            else:
                self.timeField.configure(highlightcolor="red")
        else:
            self.passFields.configure(highlightcolor="red")
    else:
        self.timeField.config(highlightbackground="red", highlightcolor="red")

Answer 1

Addressing the issue with highlightthickness

The code you've given should work, though you may be bumping up against platform implementation (ie: windows may not treat the highlightthickness the same as other platforms)

Here's a program that should work, though I haven't tested it on windows 7:

import Tkinter as tk

class Example(tk.Frame):
    def __init__(self, parent):
        tk.Frame.__init__(self, parent)

        self.entry = tk.Entry(self)
        self.button = tk.Button(self, text="Validate", command=self.validate)
        self.entry.pack(side="top", fill="x")
        self.button.pack(side="bottom")

        self.validate() # initialize the border

    def validate(self):
        data = self.entry.get()
        if len(data) == 0:
            self.entry.configure(highlightbackground="red", highlightcolor="red")
        else:
            self.entry.configure(highlightbackground="blue", highlightcolor="blue")


if __name__ == "__main__":
    root = tk.Tk()
    Example(root).pack(fill="both", expand=True)
    root.mainloop()

Using a frame to simulate a border

Another solution is to create a border with a frame that is just slightly larger than the button. Here's a quick example. Its not really production ready, but it illustrates the point:

import Tkinter as tk

class Example(tk.Frame):
    def __init__(self, parent):
        tk.Frame.__init__(self, parent)

        self.entry = CustomEntry(self)
        self.button = tk.Button(self, text="Validate", command=self.validate)
        self.entry.pack(side="top", fill="x")
        self.button.pack(side="bottom")

        self.validate() # initialize the border

    def validate(self):
        data = self.entry.get()
        if len(data) == 0:
            self.entry.set_border_color("red")
        else:
            self.entry.set_border_color("blue")

class CustomEntry(tk.Frame):
    def __init__(self, parent, *args, **kwargs):
        tk.Frame.__init__(self, parent)
        self.entry = tk.Entry(self, *args, **kwargs)
        self.entry.pack(fill="both", expand=2, padx=2, pady=2)

        self.get = self.entry.get
        self.insert = self.entry.insert

    def set_border_color(self, color):
        self.configure(background=color)

if __name__ == "__main__":
    root = tk.Tk()
    Example(root).pack(fill="both", expand=True)
    root.mainloop()

Answer 2

Altough it is an old question i stumbled upon the same problem on windows 10 and there is meanwhile a fairly simple solution.

In addition to setting the highlightbackground and color you have to change the highlightthickness to something greater zero. Bryan Oekley mentioned it in the heading of his answer but i couldnt find it in his code so here is a little code snippet.

self.entry = tk.Entry(self, highlightthickness=2)
self.entry.configure(highlightbackground="red", highlightcolor="red")

(this should maybe be a comment on Bryans Answer)