Ensure that resources gauge is not drawn with a width of 0 to make GTK happy

gui/utils/drawUtils.py

@@ -33,9 +33,10 @@ def DrawFilledBitmap(width, height, color):
     return canvas
 
 def DrawGradientBar(width, height, gStart, gEnd, gMid = None, fillRatio = 4):
+    # we need to have dimensions to draw
+    assert width > 0 and height > 0
     canvas = wx.EmptyBitmap(width,height)
 
-
     mdc = wx.MemoryDC()
     mdc.SelectObject(canvas)