Fix little errors

display.py

@@ -265,7 +265,7 @@ class DisplayHTMLBlockTableWithGraph(DisplayHTMLBlockTable):
 
     def _computeMax(self):
         for i in range(0, self.nb_valid_rows):
-            row = self.row[i]
+            row = self.rows[i]
             for j in range(1, len(row)):
                 if type(row[j]) != int:
                     continue

plugins/display/istats_diff.py

@@ -111,5 +111,7 @@ class IWLADisplayStatsDiff(IPlugin):
                 block.setCellCSSClass(idx, 0, cls)
                 if diff:
                     value = block.getCellValue(idx, self.display_index)
+                    if type(value) == int:
+                        value = str(value)
                     value += ' (+%d)' % diff
                     block.setCellValue(idx, self.display_index, value)