Bug 5774 Unpredicatable behaviour on double click in packages view
from EC: If you double click a file in the packages view, it opens the file (technically, compilation unit I believe) -- if not already open. However, if the file is already open, a single click selects it as the active editor tag; a double click expands its structure in the packages view. This is unpredictable behavior ;
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/packageview/PackageExplorerPart.java
public final static String VIEW_ID= JavaUI.ID_PACKAGES;
				
	
	static final String TAG_SELECTION= "selection"; 
	static final String TAG_EXPANDED= "expanded"; 
	static final String TAG_ELEMENT= "element"; 
	static final String TAG_PATH= "path"; 
	static final String TAG_VERTICAL_POSITION= "verticalPosition"; 
	static final String TAG_HORIZONTAL_POSITION= "horizontalPosition"; 
	static final String TAG_FILTERS = "filters"; 
	static final String TAG_FILTER = "filter"; 
	static final String TAG_SHOWLIBRARIES = "showLibraries"; 
	static final String TAG_SHOWBINARIES = "showBinaries"; 
	static final String TAG_WORKINGSET = "workingset"; 
	private JavaElementPatternFilter fPatternFilter= new JavaElementPatternFilter();
	private LibraryFilter fLibraryFilter= new LibraryFilter();
	private BinaryProjectFilter fBinaryFilter= new BinaryProjectFilter();
	private WorkingSetFilter fWorkingSetFilter= new WorkingSetFilter();
	private ProblemTreeViewer fViewer; 
	private PackagesFrameSource fFrameSource;
	private FrameList fFrameList;
	private ContextMenuGroup[] fStandardGroups;