Bug 5571 JAR Packager: Reveal first checked project
If the list of projects in the JAR Packager is long it is possible that the shown projects are not checked even though there are checked projects (due to current selection). ==> reveal the first checked project.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/jarpackager/CheckboxTreeAndListGroup.java
*	Creates this group's tree viewer.
	 */
	protected void createTreeViewer(Composite parent, int width, int height) {
		Tree tree= new Tree(parent, SWT.CHECK | SWT.BORDER);
		GridData data= new GridData(GridData.FILL_BOTH);
		data.widthHint= width;
		data.heightHint= height;
		tree.setLayoutData(data);
		fTreeViewer= new CheckboxTreeViewer(tree);
		fTreeViewer.setContentProvider(fTreeContentProvider);
		fTreeViewer.setLabelProvider(fTreeLabelProvider);
		fTreeViewer.addTreeListener(this);
		fTreeViewer.addCheckStateListener(this);
		fTreeViewer.addSelectionChangedListener(this);
	}
	/**
	 * Returns a boolean indicating whether the passed tree element should be
	 * at LEAST gray-checked.  Note that this method does not consider whether
	 * it should be white-checked, so a specified tree item which should be
	 * white-checked will result in a <code>true</code> answer from this method.
	 * To determine whether a tree item should be white-checked use method
	 * #determineShouldBeWhiteChecked(Object).
	 *
	 * @param element java.lang.Object
	 * @return boolean
	 * @see #determineShouldBeWhiteChecked(java.lang.Object)
	 */
	protected boolean determineShouldBeAtLeastGrayChecked(Object treeElement) {