[10] Review request for 8176844: Menus not always selected properly with GTK 3

[Semyon Sadetsky]

Hello Kevin & David,

Please review the fix for jfx9:

bug: https://bugs.openjdk.java.net/browse/JDK-8176844

webrev: http://cr.openjdk.java.net/~ssadetsky/8176844/

--Semyon