Correct an oversight in "TerraTheme" where the new FillPane class did not have its TerraFillPaneSkin registered in the skin map. The only difference this might make is the default background color for a FillPane, since this is the only thing implemented in this file (i.e., all the other skin functionality is in FillPaneSkin).
pivot/trunk/wtk-terra/src/org/apache/pivot/wtk/skin/terra/TerraTheme.java