Bug 11437 jar packager: no error message but buttons disabled
20020314 on the 'jar manifest' wizard page, if you select to use existing manifest file there's no error message but next and finish are disabled user should be informed what to do to make the wizard happy
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/jarpackager/JarManifestWizardPage.java
Label spacer= new Label(parent, SWT.NONE);
		GridData data= new GridData();
		data.horizontalAlignment= GridData.FILL;
		data.verticalAlignment= GridData.BEGINNING;
		spacer.setLayoutData(data);
	}
	/**
	 * Returns the resource for the specified path.
	 *
	 * @param path	the path for which the resource should be returned
	 * @return the resource specified by the path or <code>null</code>
	 */
	protected IResource findResource(IPath path) {
		IWorkspace workspace= JavaPlugin.getWorkspace();
		IStatus result= workspace.validatePath(
							path.toString(),
							IResource.ROOT | IResource.PROJECT | IResource.FOLDER | IResource.FILE);
		if (result.isOK() && workspace.getRoot().exists(path))
			return workspace.getRoot().findMember(path);
		return null;
	}
	protected IPath getPathFromString(String text) {
		return new Path(text).makeAbsolute();
	}
	/**
	 * Creates a selection dialog that lists all packages under the given package 
	 * fragment root.
	 * The caller is responsible for opening the dialog with <code>Window.open</code>,
	 * and subsequently extracting the selected packages (of type
	 * <code>IPackageFragment</code>) via <code>SelectionDialog.getResult</code>.