title: Need Help Binding, .get()-ing, appending in Tkinter GUI with Entry box
body: <p>The thing is, I've expanded on this code more, and I am having another problem: The binding function is being ignored or something when I run this code (Of course I have my window setup above this as always):</p>
  
  <pre><code>from tkinter import *
  #Window setup, ignore this mostly
  app = Tk()
  app.title('Geometry Calculator')
  app.geometry('384x192+491+216')
  app.iconbitmap('Geo.ico')
  app.minsize(width=256, height=96)
  app.maxsize(width=384, height=192)
  app.configure(bg='WhiteSmoke')
  
  PointList = []
  
  
  def AddCheck(event):
      Point = e1.get()
      PointTest = Point
      if PointTest.find(',') is True:
          PTest_X = PointTest[0].split(',')
          PTest_Y = PointTest[1].split(',')
          try:
              PTest_X = float(PTest_X)
              PTest_Y = float(PTest_Y)
              PointList.append(Point)
              l1 = Label(app, text='PointList').grid(row=1, column=0)
              e1.delete(0, END)
          except:
              print('Error: Invalid point format.')
      if PointTest.find(',') is False:
          print('Error: Invalid point format.')
  
  e1 = Entry(app)
  e1.grid(row=0, column=0, sticky=W)
  Entry.bind(e1, '&lt;Return&gt;', AddCheck)
  mainloop()
  </code></pre>
  
  <p>Basically, my goal was to make a "checker" or whatever you might call it for the string entered into the Entry box. I am dealing with coordinates, so the first thing I wanted to do was to see if the string contained a comma. If it doesn't contain one, I automatically signal an error to the Terminal, and I will to the window later. The comma will split up the two main parts of the string I will be operating on in the ultimate function of this program. So, I split the string from the comma into the two parts. Then I wanted to see if the split parts of the string (PTest_X and PTest_Y) could be converted into floats with a Try statement, which obviously means only integers or floating point numbers that are before or after the comma will work under a conversion. The Except part of the Try statement just tells to return an error to the Terminal as well, like before. So, if PTest_X and PTest_Y can be converted, that's when I finally want to append them to a list, make a label of the list, and do whatever else.</p>
  
  <p>The point of this "checker" system is to give feedback to the user telling them that their coordinate point "syntax", if you will, is incorrect. I would rather implement this system at this point to tell the user they have entered in a point incorrectly rather than telling them them the this after everything has already been processed.</p>
  
  <p>I am doing this for user friendliness, which TRULY always comes first when it comes to user interaction. I hope to alleviate any pain from the user's experience with the program.</p>