Bug 119528 [build path] "Add Java Source Attachment" default path should be Jar's path
When using Buildpath Jar-> Properties -> Add Java Source Attachment -> (External File Or External Folder), the default folders for the browse dialog can be improved to improve usability and productivity. The most appropriate starting folder for the dialog is surely the folder containing the Jar for which we are setting the source path, since the soource archive or folder will likely be nearby (ie locality principle). Currently, I am getting "My documents" for source folder everytime, and I waste valuable effoct navigating around to the network drive where our library archives are maintained. Similar behavior for source archives zips.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/buildpaths/SourceAttachmentBlock.java
private IStatusChangeListener fContext;
	
	private StringButtonDialogField fFileNameField;
	private SelectionButtonDialogField fWorkspaceButton;
	private SelectionButtonDialogField fExternalFolderButton;
	
	private IStatus fNameStatus;
	
	/**
	 * The path to which the archive variable points.
	 * Null if invalid path or not resolvable. Must not exist.
	 */	
	private IPath fFileVariablePath;
		
	private IWorkspaceRoot fWorkspaceRoot;
	
	private Control fSWTWidget;
	private CLabel fFullPathResolvedLabel;
	
	private IJavaProject fProject;
	private IClasspathEntry fEntry;
	private IPath fContainerPath;
	/**
	 * @param context listeners for status updates
	 * @param entry The entry to edit
	 */
	public SourceAttachmentBlock(IStatusChangeListener context, IClasspathEntry entry) {
		Assert.isNotNull(entry);