Bug 341273 ESS will not work without parts
While windows without any parts probably isn't a very interesting shape, it is still possible to create such a thing. In this scenario, the ESS may not work properly because we rely solely on the active part for selection information. It should be possible to have a selection at the window level as-is.
bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/internal/workbench/SelectionServiceImpl.java
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