Bug 6579 Packages view: can't open MANIFEST.MF of JAR file
1. Drill into a JAR with a manifest file (MANIFEST.MF) in the Packages view. Note: The JAR must be on the build path. 2. Double-click MANIFEST.MF -> nothing happens 3. From the context menu select "Open" -> nothing happens I used ant.jar in org.eclipse.ant.core as my test case.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/EditorUtility.java
toggleAction.setEditor((ITextEditor)editorPart);
			
			toggleAction.setEditor(null);
		}
	}
	
	/**
	 *@deprecated	Made it public again for java debugger UI.
	 */
	public static String getEditorID(IEditorInput input, Object inputObject) {
		IEditorRegistry registry= PlatformUI.getWorkbench().getEditorRegistry();
		IEditorDescriptor descriptor= registry.getDefaultEditor(input.getName());
		if (descriptor != null)
			return descriptor.getId();
		return null;
	}
	
	private static IEditorInput getEditorInput(IJavaElement element) throws JavaModelException {
		while (element != null) {			
			if (element instanceof ICompilationUnit) {
				ICompilationUnit unit= JavaModelUtil.toOriginal((ICompilationUnit) element);
					IResource resource= unit.getResource();
					if (resource instanceof IFile)
						return new FileEditorInput((IFile) resource);
			}
			
			if (element instanceof IClassFile)
				return new InternalClassFileEditorInput((IClassFile) element);