Created attachment 332428 [details]
nautilus screenshoots after the error occurs

My system:
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- Debian testing (GNU/Linux 64 bit)
- Nautilus Version: 3.20.1-3 (debian testing)


Steps to Reproduce and Results:
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CASE A: open a document using nautilus

1) open nautilus
2) test mouse over GUI effect on the sidebar --> bug does not occur (links at the sidebar are in dark grey standard color during mouse over) --> GUI as expected
3) open a document (e.g. *.txt or *.png) --> during the open process for the document all links at the sidebar are in light grey color (until the external program is opened) --> GUI as expected
4) close external program (e.g. for *.txt or *.png) --> links at the sidebar are in dark grey standard color --> GUI as expected
5) test mouse over GUI effect on the sidebar --> bug occurs (see attachment): links are partial in dark grey standard color and partial in light grey color 


CASE B: use an other program (e.g. firefox)

1) open an other program (e.g. firefox)
2) open nautilus
3) test mouse over GUI effect on the sidebar --> bug does not occur (links at the sidebar are in dark grey standard color during mouse over) --> GUI as expected
4) switch back to firefox 
5) switch back to nautilus
6) test mouse over GUI effect on the sidebar --> bug occurs (see attachment): links are partial in dark grey standard color and partial in light grey color