<Swing Dev> [11] RFR JDK-7190978:javax/swing/JComponent/7154030/bug7154030.java fails on windows, mac

[Prasanta Sadhukhan]

Hi All,

Please review a testbug fix for an issue whereby it seen that it fails 
citing "failing to hide opaque button".
It is seen that the test compares the buffered image strictly 
pixel-by-pixel and even if it differs by 1,2 pixels it fails which is 
what was happening here.
Proposed fix is to make it more lenient by allowing a tolerance of 
20pixels difference in the comparison of 2 bufferedimage.
It is verified on windows, mac.

Bug: https://bugs.openjdk.java.net/browse/JDK-7190978
webrev: http://cr.openjdk.java.net/~psadhukhan/7190978/webrev.00/

Regards
Prasanta