Bug 273489 [Mac] We should not nest sheets
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/ide/dialogs/PathVariableDialog.java
* Used when validating the user input.
     */
    private int validationStatus;
    /**
     * The current validation message generated by the last
     * call to a <code>validate</code> method.
     */
    private String validationMessage;
    /**
     * Whether a variable name has been entered.  
     */
    private boolean nameEntered = false;
    /**
     * Whether a variable location has been entered.  
     */
    private boolean locationEntered = false;
    /**
     * The standard message to be shown when there are no problems being
     * reported.
     */
    final private String standardMessage;
    /**
     * Constant for defining this dialog as intended to create a new variable
     * (value = 1).
     */
    public final static int NEW_VARIABLE = 1;
    /**
     * Constant for defining this dialog as intended to edit an existing
     * variable (value = 2).
     */