The viewer is now cleared when the AtomSelection dialog is closed

MDANSE/Framework/Plugins/AnimationPlugin.py

MDANSE/Framework/Plugins/DataPlugin.py

MDANSE/Framework/Plugins/IPlugin.py

MDANSE/Framework/Plugins/MolecularViewerPlugin.py

MDANSE/Framework/Status.py

MDANSE/Framework/Widgets/AtomSelectionWidget.py

MDANSE/Framework/Widgets/IWidget.py

MDANSE/Framework/Widgets/InstrumentResolutionWidget.py

MDANSE/Framework/Widgets/McStasParametersWidget.py

MDANSE/Framework/Widgets/UserDefinitionWidget.py

MDANSE/GUI/DataController.py

MDANSE/GUI/DataTreePanel.py

MDANSE/GUI/JobControllerPanel.py

MDANSE/GUI/PluginsTreePanel.py

MDANSE/GUI/WorkingPanel.py