et value of "ph" to 0 if division by zero takes place

src/sugar3/graphics/palettewindow.py

@@ -971,6 +971,10 @@ class Invoker(GObject.GObject):
 
             ih = 0
             
+            if palette_dim.width == 0:
+                ph = 0
+
+            else:
                 # Set palette_halign to align to screen on left
                 if dleft > dright:
                     ph = -float(dleft) / palette_dim.width