title: Python 3 Tkinter: Grid columnspan ignored
body: <p>My <code>grid</code> <code>columnspan</code> is ignored in the following code. The <code>"Ok"</code> button doesn't occupy full <code>width</code>.</p>
  
  <pre><code>class Arshi(tk.Frame):
      def __init__(self, *args, **kwargs):
          tk.Frame.__init__(self, *args, **kwargs)
          self.fontOption = tk.Toplevel()
  
          self.selectFont = tk.Label(self.fontOption, text="Select Font: ", font=("Courier New", 9))
          self.selectFont.grid(row=0, columnspan=1)
  
          self.selectedFont = tk.StringVar()
          self.fontComboBox = ttk.Combobox(self.fontOption, textvariable=self.selectedFont)
          self.fontComboBox.grid(row=0, column=1, columnspan=1)
  
          self.selectFontSize = tk.Label(self.fontOption, text="Font Size: ", font=("Courier New", 9))
          self.selectFontSize.grid(row=1, columnspan=1)
  
          self.selectedFontSize = tk.StringVar()
          self.fontSizeComboBox = ttk.Combobox(self.fontOption, textvariable=self.selectedFontSize)
          self.fontSizeComboBox.grid(row=1, column=1, columnspan=1)
  
          self.fontProceed = tk.Button(self.fontOption, text="Ok", font=("Courier New", 9))
          self.fontProceed.grid(row=2, column=0, columnspan=2)
  
  if __name__ == "__main__":
      root = tk.Tk()
      root.title("Arshi")
      root.geometry("1024x600")
      window = Arshi(root).pack(side="top", fill="both", expand=True)
      root.mainloop()
  </code></pre>