7160623: [macosx] Editable TextArea/TextField are blocking GUI applications from exit

Reviewed-by: anthony, art

src/macosx/classes/sun/lwawt/LWComponentPeer.java

@@ -372,7 +372,7 @@ public abstract class LWComponentPeer<T extends Component, D extends JComponent>
     }
 
     @Override
-    public void dispose() {
+    public final void dispose() {
         if (disposed.compareAndSet(false, true)) {
             disposeImpl();
         }

src/macosx/classes/sun/lwawt/LWTextComponentPeer.java

@@ -81,6 +81,18 @@ abstract class LWTextComponentPeer<T extends TextComponent, D extends JComponent
         firstChangeSkipped = true;
     }
 
+    @Override
+    protected final void disposeImpl() {
+        synchronized (getDelegateLock()) {
+            // visible caret has a timer thread which must be stopped
+            getTextComponent().getCaret().setVisible(false);
+        }
+        super.disposeImpl();
+    }
+
+    /**
+     * This method should be called under getDelegateLock().
+     */
     abstract JTextComponent getTextComponent();
 
     public Dimension getPreferredSize(final int rows, final int columns) {