8027157: [SwingNode] needs explicit expose for JWindow

Reviewed-by: art, anthony

src/windows/classes/sun/awt/windows/WComponentPeer.java

@@ -1108,4 +1108,8 @@ public abstract class WComponentPeer extends WObjectPeer
     }
 
     private native void setZOrder(long above);
+
+    public boolean isLightweightFramePeer() {
+        return false;
+    }
 }

src/windows/classes/sun/awt/windows/WLightweightFramePeer.java

@@ -90,4 +90,8 @@ public class WLightweightFramePeer extends WFramePeer {
     public void updateCursorImmediately() {
         SwingAccessor.getJLightweightFrameAccessor().updateCursor((JLightweightFrame)getLwTarget());
     }
+
+    public boolean isLightweightFramePeer() {
+        return true;
+    }
 }

src/windows/classes/sun/awt/windows/WWindowPeer.java

@@ -252,6 +252,13 @@ public class WWindowPeer extends WPanelPeer implements WindowPeer,
                 updateWindow(true);
             }
         }
+
+        // See https://javafx-jira.kenai.com/browse/RT-32570
+        WComponentPeer owner = getNativeParent();
+        if (owner != null && owner.isLightweightFramePeer()) {
+            Rectangle b = getBounds();
+            handleExpose(0, 0, b.width, b.height);
+        }
     }
 
     // Synchronize the insets members (here & in helper) with actual window