              The Combobox widget
          """
          logger.debug("Adding scale combo")
          self.scale_var.set("100%")
          scale = ttk.Combobox(self,
                               textvariable=self.scale_var,
                               values=["Fit"],
                               state="readonly",
                               width=10)
          scale.pack(side=tk.RIGHT)
 
</s> remove         slider = tk.Scale(self,
 </s> add         slider = tk.Scale(self._frame, </s> remove         self.pack(side=tk.BOTTOM, fill=tk.X, padx=2, pady=2)
 </s> add             self._frame.pack(side=tk.BOTTOM, fill=tk.X, padx=2, pady=2)

        scale = ttk.Combobox(self._frame,
              The Combobox widget
          """
          logger.debug("Adding scale combo")
          self.scale_var.set("100%")
        scale = ttk.Combobox(self._frame,
                               textvariable=self.scale_var,
                               values=["Fit"],
                               state="readonly",
                               width=10)
          scale.pack(side=tk.RIGHT)
keep keep keep keep replace keep keep keep keep keep
 GUI - Preview updates
  - Training preview. Embed preview pop-out window
  - Bugfix - convert/extract previews 
lib/training/preview_tk.py