<Swing Dev> [12] RFR JDK-8218473: JOptionPane display issue with GTKLookAndFeel

[Semyon Sadetsky]

Hello,

Please review a fix for JDK 12.

JBS: https://bugs.openjdk.java.net/browse/JDK-8218473

webrev: http://cr.openjdk.java.net/~ssadetsky/8218473/webrev.00/

This is a JCK test failure fix. The test fails under the GTKLookAndFeel 
on Linux platforms with gtk+-3.20+ library installed.

Starting gtklib- 3.20 the  widget drawing styles were totally reworked 
so the text selection background cannot be obtained using TEXT_FIELD 
widget anymore. To fix that the corresponding request is redirected to 
the TEXT_AREA widget. The fix was tested on all major supported Linux 
platforms.

--Semyon