code: def color_group(self, checked=False, test_color=None):
          
          group = self.tabs.currentWidget()
          if test_color is None:
              newcolor = QColorDialog.getColor(group.idx_color)
          else:
              newcolor = test_color
          group.idx_color = newcolor
  
          self.apply()
docs: Change the color of the group.