title: ttk:Combobox foreground color change doesn't work properly. What's wrong?
body: <p>Attemps to reliably change the text color in a ttk::Combobox fail.
  It happens for me on Windows 10 with the native theme.</p>
  <p>The following code creates two comboboxes with their foreground color set to red.
  Selecting an option in one of them then the other, back and forth, shows that the foreground color alternates between black and red.</p>
  <pre><code>import tkinter as tk
  from tkinter import ttk
  
  root = tk.Tk()
  ttk.Style().configure('Red.TCombobox', foreground='red')
  combo = ttk.Combobox(root, values=('one', 'two', 'three'), state='readonly')
  combo.configure(style='Red.TCombobox')
  combo.grid(row=0, column=0)
  combo2 = ttk.Combobox(root, values=('one', 'two', 'three'), state='readonly')
  combo2.configure(style='Red.TCombobox')
  combo2.grid(row=0, column=1)
  root.mainloop()
  </code></pre>
  <p>Here's what it looks like:</p>
  <p><a href="https://i.stack.imgur.com/aDbFE.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/aDbFE.png" alt="combo foreground color illustration" /></a></p>
  <p>How can I make it red at least when the text is not marked as selected?
  (a solution for the selected text would be appreciated as well)</p>