title: Cannot type in Python Entry Widget
body: <p>I've got an interesting problem with the tk Entry widget. If I run the following test code,</p>
  
  <pre><code>from Tkinter import *
  root =Tk()
  def pfunc(self):
      print Input.get()
  f=Frame(root)
  f.pack()
  Input=Entry(f)
  #Input.bind("&lt;Return&gt;",pfunc)
  Input.pack()
  root.mainloop()
  </code></pre>
  
  <p>I can properly enter into the widget and print to console; however the following code, as part of a larger GUI, does not allow me to click in the Entry boxes at all.</p>
  
  <pre><code>    self.Tlabel = Label(self.TempFrame, text="Temp")
      self.Tlabel.pack( side = LEFT)
      self.Tenter = Entry(self.TempFrame,width=10, bd =5)
      self.Tenter.bind("&lt;Return&gt;",self.getFlux)
      self.Tenter.pack (side=RIGHT)
      self.Flabel = Label(self.FluxFrame, text="Flux")
      self.Flabel.pack( side = LEFT)
      self.Fenter = Entry(self.FluxFrame, width=10, bd =5)
      self.Fenter.bind("&lt;Return&gt;",self.getTemp)
      self.Fenter.pack(side = RIGHT)
  
  def getFlux(self):
      for i in range(len(self.fit_tuples)):
          if self.fit_tuples[i][0]==self.currentBFMdate and self.fit_tuples[i][1]==self.cell.get():
              fit_data=self.fit_tuples[i][2]
              self.Fenter.set(fit_data[0]*np.exp(fit_data[1]*int(self.Tenter.get())))
          else:
              self.Fenter.set("Invalid")
  
  def getTemp(self):
      for i in range(len(self.fit_tuples)):
          if self.fit_tuples[i][0]==self.currentBFMdate and self.fit_tuples[i][1]==self.cell.get():
              fit_data=self.fit_tuples[i][2]
              self.Tenter.set(np.log(float(self.Fenter.get())/fit_data[0])/fit_data[1])
          else:
              self.Tenter.set("Invalid")
  </code></pre>
  
  <p>Furthermore, if I run both codes on a separate windows PC I have the same problem.  The only difference I can possibly think of is that I am using instance variables within a class; but it seems that other widgets are bound and working properly.</p>