temporarily disable block-level background colors for Qt versions 4.7 and higher

This avoids the crash in BZDNG-193. Hopefully we will be able to reverse it,
once the trolltech guys fix the bug upstream.

modules/gui/src/python_shell/python_syntax_highlighter.cc

@@ -86,7 +86,9 @@ void PythonSyntaxHighlighter::highlightBlock(const QString& text_block) {
   } else if (currentBlockState() & BLOCKTYPE_CODE) {
     base_state=BLOCKTYPE_CODE;
   }
+#if QT_VERSION < 0x040700
   cursor.setBlockFormat(block_formats_[static_cast<BlockType>(base_state)]);
+#endif
   if (currentBlockState() & BLOCKTYPE_BLOCKEDIT || 
       currentBlockState() & BLOCKTYPE_ACTIVE || 
       currentBlockState() & BLOCKTYPE_CODE) {