Bug 8476 JAR Packager: Make main class field editable
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/jarpackager/JarManifestWizardPage.java
fMainClassBrowseButton.addSelectionListener(new SelectionAdapter() {
			public void widgetSelected(SelectionEvent e) {
				handleMainClassBrowseButtonPressed();
			}
		});
	}
	
	
		
	private void update() {
		updateModel();
		updateEnableState();
		updatePageCompletion();
	}
	
	/**
	 *	Open an appropriate dialog so that the user can specify a manifest
	 *	to save
	 */
	protected void handleNewManifestFileBrowseButtonPressed() {
		
		SaveAsDialog dialog= new SaveAsDialog(getContainer().getShell());
		dialog.create();
		dialog.getShell().setText(JarPackagerMessages.getString("JarManifestWizardPage.saveAsDialog.title")); 
		dialog.setMessage(JarPackagerMessages.getString("JarManifestWizardPage.saveAsDialog.message")); 
		dialog.setOriginalFile(createFileHandle(fJarPackage.getManifestLocation()));
		if (dialog.open() == dialog.OK) {
			fJarPackage.setManifestLocation(dialog.getResult());
			fNewManifestFileText.setText(dialog.getResult().toString());
		}