'Highlight current cell'

def highlight_current_cell(self):

    if ((self.cell_separators is None) or (not self.highlight_current_cell_enabled)):
        return
    selection = QTextEdit.ExtraSelection()
    selection.format.setProperty(QTextFormat.FullWidthSelection, to_qvariant(True))
    selection.format.setBackground(self.currentcell_color)
    (selection.cursor, whole_file_selected, whole_screen_selected) = self.select_current_cell_in_visible_portion()
    if whole_file_selected:
        self.clear_extra_selections('current_cell')
    elif whole_screen_selected:
        if self.has_cell_separators:
            self.set_extra_selections('current_cell', [selection])
            self.update_extra_selections()
        else:
            self.clear_extra_selections('current_cell')
    else:
        self.set_extra_selections('current_cell', [selection])
        self.update_extra_selections()
