<Swing Dev> <AWT Dev> [8] Review Request: JDK-8027157 [SwingNode] needs explicit expose for JWindow

[Anton V. Tarasov]

Hello,

Please, review the fix:

jira: https://bugs.openjdk.java.net/browse/JDK-8027157
webrev: http://cr.openjdk.java.net/~ant/RT-32570/webrev.0

This is to support SwingNode. On Windows, in the interop mode, when a 
popup (JWindow) is shown it doesn't get WM_PAINT native message.
The message should trigger adding a dirty component to RepaintManager 
that will eventually paint it.
Currently, a popup is shown blank. Please, see 
https://javafx-jira.kenai.com/browse/RT-32570 for more details.

The fix explicitly calls for WWindowPeer.handleExpose(..) on showing a 
window owned by JLightweightFrame.

Thanks,
Anton.