unused osm server address box shows red border

[Klumbumbus]

What steps will reproduce the problem?

1. open preferences
2. click projection tab
3. use default server is checked
4. The text box below has a red border (like when there is a wrong url), however it is not in use at all

5. uncheck and check again the use default server check box removes the red border

URL:http://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2016-01-28 22:19:39 +0100 (Thu, 28 Jan 2016)
Build-Date:2016-01-29 02:33:28
Revision:9664
Relative:URL: ^/trunk

Identification: JOSM/1.5 (9664 de) Windows 7 32-Bit
Memory Usage: 247 MB / 742 MB (85 MB allocated, but free)
Java version: 1.8.0_71-b15, Oracle Corporation, Java HotSpot(TM) Client VM
VM arguments: [-Djava.security.manager, -Djava.security.policy=file:C:\Program Files\Java\jre1.8.0_71\lib\security\javaws.policy, -DtrustProxy=true, -Djnlpx.home=<java.home>\bin, -Djnlpx.origFilenameArg=C:\Program Files\josm-latest-bla.jnlp, -Djnlpx.remove=false, -Djava.util.Arrays.useLegacyMergeSort=true, -Djnlpx.heapsize=256m,768m, -Djnlpx.splashport=58258, -Djnlpx.jvm=<java.home>\bin\javaw.exe, -Djnlpx.vmargs=LURqYXZhLnV0aWwuQXJyYXlzLnVzZUxlZ2FjeU1lcmdlU29ydD10cnVlAA==]
Dataset consistency test: No problems found

Plugins:
- AddrInterpolation (31772)
- DirectDownload (31934)
- DirectUpload (31912)
- HouseNumberTaggingTool (31772)
- OpeningHoursEditor (31772)
- PicLayer (31895)
- RoadSigns (31895)
- apache-commons (31895)
- buildings_tools (31895)
- download_along (31772)
- editgpx (31772)
- imagery_offset_db (31895)
- importvec (31772)
- log4j (31895)
- measurement (31895)
- photo_geotagging (31895)
- photoadjust (32016)
- public_transport (31895)
- reltoolbox (31895)
- reverter (32005)
- tag2link (31910)
- tageditor (31772)
- tagging-preset-tester (31895)
- terracer (31895)
- turnlanes (31772)
- turnrestrictions (31895)
- undelete (31895)
- utilsplugin2 (32018)
- wikipedia (32003)