Bug 39027 [working sets] Edit active working set prevents removal of closed projects.
When editing the "active working set" closed projects cannot be removed from the working set, the project has to be opened so it can be removed. This is a minor usability issue.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/workingsets/JavaWorkingSetPage.java
});
		if (fWorkingSet != null)
			fWorkingSetName.setText(fWorkingSet.getName());
		initializeCheckedState();
		disableClosedProjects();
		validateInput();
		Dialog.applyDialogFont(composite);
		 
		JavaUIHelp.setHelp(fTree, IJavaHelpContextIds.JAVA_WORKING_SET_PAGE);
	}
	/*
	 * Implements method from IWorkingSetPage
	 */
	public IWorkingSet getSelection() {
		return fWorkingSet;
	}
	/*
	 * Implements method from IWorkingSetPage
	 */
	public void setSelection(IWorkingSet workingSet) {
		Assert.isNotNull(workingSet, "Working set must not be null"); 
		fWorkingSet= workingSet;
		if (getContainer() != null && getShell() != null && fWorkingSetName != null) {
			fFirstCheck= false;
			fWorkingSetName.setText(fWorkingSet.getName());
			initializeCheckedState();
			disableClosedProjects();
			validateInput();
		}
	}