<Swing Dev> RFR: 8240202 A few client tests leave mouse buttons pressed

[Sergey Bylokhov]

Hello.
Please review the fix for jdk/client.

Bug: https://bugs.openjdk.java.net/browse/JDK-8240202
Fix: http://cr.openjdk.java.net/~serb/8240202/webrev.00

Two tests leave the mouse button pressed:
   test/jdk/javax/swing/JButton/PressedButtonRightClickTest.java : affects our CI
   test/jdk/java/awt/Mixing/AWT_Mixing/JSplitPaneOverlapping.java : not a big issue, the test is in the problem list already

-- 
Best regards, Sergey.