SplitPane Divider Color not consistent in Vertical split in GTK L&F.

Steps to reproduce:
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1) Run SwingSet2 in the PIT build of 13th Sept.
2) Set the L&F to GTK
3) Go to JSplitPane Demo
4) Uncheck Continous Layout check box.
5) check Vertically Split check box.
6) Now drag the divider.
7) Notice that the color of the divider bar is not consistent.
8) This is unlike the color divider bar in Horizontal split