title: Populating a Glade combobox "gtk_entry_set_text: assertion `text != NULL' failed"?
body: <p>I am building a “pseudo-intelligent” GUI for a gimp plugin using Glade. The main part of the GUI has two frames and imports the contents using the “reparent” method. The main objective is to have the contents of the second frame determined by the selections made in the first frame. (Eventually, the intention is to import this GUI as the content for the tabbed pages of a "notebook")</p>
  
  <p>To start with, I made a simple window, consisting of a “RadioButtonBox” and a “ComboBox” which is populated using:</p>
  
  <pre><code># create the cell renderer
  self.cell = gtk.CellRendererText()
  #populate the default choice into the Selection  combobox
  self.SelectionBox = self.builder.get_object("SelectionBox")
  self.SelectionBox.set_model(self.EditCommands)
  self.SelectionBox.pack_start(self.cell, True)
  self.SelectionBox.add_attribute(self.cell, 'text', 1)
  self.SelectionBox.set_active(0)
  # End: populate the selection combo box section
  </code></pre>
  
  <p>This works and I can successfully “import” and “reparent” the simple GUI as the first frame of the larger, more complex GUI without any problems. However, as the design progressed, it has become more convenient to have the code for the first frame as an integral part of the main GUI, and this is where my problems begin.</p>
  
  <p>I have reproduced the contents of the simple GUI in the first frame of the larger GUI and copy/pasted the code from the simple GUI's “<strong>init</strong>” function. In other-words, everything is identical.</p>
  
  <p>Unfortunately, when I run the code I get the following error:</p>
  
  <pre><code>C:\Documents and Settings\anonymous\Desktop\Glade-tutorial\BatchEditMain\BatchEditLibrary\Tab.py:46: GtkWarning: gtk_entry_set_text: assertion `text != NULL' failed
    self.SelectionBox.set_active(0)
  </code></pre>
  
  <p>Could someone please explain what the problem is?</p>
  
  <p>Thanks in advance</p>
  
  <p>Irvine</p>