code: def _create_analysis_extent_action(self):
          
          icon = resources_path('img', 'icons', 'set-extents-tool.svg')
          self.action_extent_selector = QAction(
              QIcon(icon),
              self.tr('Set Analysis Area'),
              self.iface.mainWindow())
          self.action_extent_selector.setStatusTip(self.tr(
              'Set the analysis area for InaSAFE'))
          self.action_extent_selector.setWhatsThis(self.tr(
              'Set the analysis area for InaSAFE'))
          self.action_extent_selector.triggered.connect(
              self.show_extent_selector)
          self.add_action(self.action_extent_selector)
docs: Create action for analysis extent dialog.