ADDITIONAL SYSTEM INFORMATION :
System: Windows 10 1803. | JRE and JDK: 10.0.2 and 1.8.0.191.

A DESCRIPTION OF THE PROBLEM :
It's semi-light-hard to reproduce, I thought it was a problem in JMetro, but I tried without JMetro css, and got the same thing. This bug is difficult to reproduce, but it is often noticed and people have written to me about this behavior, just try to click on the headlines.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Create TreeView component on scene.
2. Add to TreeView 1 root TreeView item.
3. Set property isShowRoot to false.
4. Add 2 TreeView expandable items.
5. Add some qty items in expandable items.
6. Set expandable items property isExpanded to true.
7. Run application with TreeView.
8. Click randomly on expandable items.
9. Click on latest item and see bug.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Normal behavior in TreeView expandable items.
ACTUAL -
Actually symbols ">" on expandable items not-correctly change if i make "Steps to Reproduce".

Gif with issue: https://user-images.githubusercontent.com/39625750/50225544-e950eb80-03b1-11e9-91ce-f6600f1c7a96.gif (GitHub resources)

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https://gist.github.com/MairwunNx/ebec5d1db72beabc412d195d0e31e9db - link on issue (gist resources)
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CUSTOMER SUBMITTED WORKAROUND :
None.

FREQUENCY : occasionally