Fix crash on new gcode file load if no previous file was loaded

gviz.py

@@ -61,8 +61,10 @@ class gviz(wx.Panel):
         self.layerindex=0
         self.showall=0
         self.dirty=1
+        self.blitmap=wx.EmptyBitmap(self.GetClientSize()[0],self.GetClientSize()[1],-1)
         self.repaint()
         
+        
     def layerup(self):
         if(self.layerindex+1<len(self.layers)):
             self.layerindex+=1
@@ -173,7 +175,8 @@ class gviz(wx.Panel):
             
 if __name__ == '__main__':
     app = wx.App(False)
-    main = window(open("/home/kliment/designs/spinner/gearend_export.gcode"))
+    #main = window(open("/home/kliment/designs/spinner/gearend_export.gcode"))
+    main = window(open("jam.gcode"))
     main.Show()
     app.MainLoop()
 

pronterface.py

@@ -642,7 +642,7 @@ class PronterWindow(wx.Frame,pronsole.pronsole):
                 return
             path = os.path.split(name)[0]
             if path != self.settings.last_file_path:
-	            self.set("last_file_path",path)
+                self.set("last_file_path",path)
             if name.lower().endswith(".stl"):
                 self.skein(name)
             else: