Bug 26109 [Dialogs] Need a FormData version of the button sizing API
The button sizing API in Dialog assumes the developer wants a GridData. We should promote the FormData version in PathVariablesDialog to Dialog.
bundles/org.eclipse.jface/src/org/eclipse/jface/dialogs/Dialog.java
if (shell != null) {
			shell.setDefaultButton(button);
		}
	}
	button.setFont(parent.getFont());
	buttons.put(new Integer(id), button);
	setButtonLayoutData(button);
	
	return button;
}
/**
 * Creates and returns the contents of this dialog's 
 * button bar.
 * <p>
 * The <code>Dialog</code> implementation of this framework method
 * lays out a button bar and calls the <code>createButtonsForButtonBar</code>
 * framework method to populate it. Subclasses may override.
 * </p>
 * <p>
 * The returned control's layout data must be an instance of 
 * <code>GridData</code>.
 * </p>
 * 
 * @param parent the parent composite to contain the button bar
 * @return the button bar control
 */
protected Control createButtonBar(Composite parent) {
	Composite composite = new Composite(parent, SWT.NONE);
	
	GridLayout layout = new GridLayout();