def _add_fold_decoration(self, block, region):
        """
        Add fold decorations (boxes arround a folded block in the editor
        widget).
        """
        deco = TextDecoration(block)
        deco.signals.clicked.connect(self._on_fold_deco_clicked)
        deco.tooltip = region.text(max_lines=25)
        deco.draw_order = 1
        deco.block = block
        deco.select_line()
        deco.set_outline(drift_color(
            self._get_scope_highlight_color(), 110))
        deco.set_background(self._get_scope_highlight_color())
        deco.set_foreground(QtGui.QColor('#808080'))
        self._block_decos.append(deco)
        self.editor.decorations.append(deco)
Add fold decorations (boxes arround a folded block in the editor
        widget).