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/JarPackageWizardPage.java
*	Stores the widget values in the JAR package.
	 */
	protected void updateModel() {
		if (getControl() == null)
			return;
		
		
		fJarPackage.setSelectedElements(getSelectedResources());
		fJarPackage.setExportClassFiles(fExportClassFilesCheckbox.getSelection());
		fJarPackage.setExportJavaFiles(fExportJavaFilesCheckbox.getSelection());
		
		fJarPackage.setJarLocation(getPathFromString(fDestinationNamesCombo.getText()));
		
		fJarPackage.setCompress(fCompressCheckbox.getSelection());
		fJarPackage.setOverwrite(fOverwriteCheckbox.getSelection());
	}
	protected IPath getPathFromString(String text) {
		return new Path(text).makeAbsolute();
	}
	/**
	 * Returns a boolean indicating whether the passed File handle is
	 * is valid and available for use.
	 *
	 * @return boolean
	 */
	protected boolean ensureTargetFileIsValid(File targetFile) {
		if (targetFile.exists() && targetFile.isDirectory()) {
			setErrorMessage(JarPackagerMessages.getString("JarPackageWizardPage.error.exportDestinationMustNotBeDirectory")); 
			fDestinationNamesCombo.setFocus();
			return false;