When selecting multiple images just after opening an HDF5 file, the "View in a new window" feature does not work (`KeyError` exception)

[PierreRaybaut]

Example of traceback in the internal console:

Traceback (most recent call last):
  File "\guidata\guidata\qthelpers.py", line 336, in <lambda>
    action.triggered.connect(lambda checked=False: triggered())
                                                   ^^^^^^^^^^^
  File "\DataLab\cdl\core\gui\panel\base.py", line 1110, in open_separate_view
    self.add_plot_items_to_dialog(dlg, oids)
  File "\DataLab\cdl\core\gui\panel\base.py", line 1076, in add_plot_items_to_dialog
    item = obj.make_item(update_from=self.plothandler[obj.uuid])
                                     ~~~~~~~~~~~~~~~~^^^^^^^^^^
  File "\DataLab\cdl\core\gui\plothandler.py", line 105, in __getitem__
    raise exc
  File "\DataLab\cdl\core\gui\plothandler.py", line 96, in __getitem__
    return self.__plotitems[oid]
           ~~~~~~~~~~~~~~~~^^^^^
KeyError: 'c39e12c3-8917-4d36-9ddd-fb539b7623c0'

This is happening because, when opening an HDF5 file and selecting multiple images, image plot items have not yet been constructed except the last image selected (due to the optimization that aims at constructing only the plot items that are visible).