fixed bug when checking out-of-bounds frames im graphics definitions

- this bug was caused by getFixedGraphicSource() always using 32x32 tile
  size even if element graphic was defined using smaller tile size like
  16x16, resulting in correct definitions to be assumed as out of bounds
- fixed by using getGraphicSourceXY() instead, which only uses width and
  height attributes (which are set to the correct tile size for elements)