Unexpected action on list when press right key

[anonymous]

What steps will reproduce the problem?

1.Open Imagery from menu bar
2.Move mouse cursor to end of list on "More" option (screenshot)
3.Press right on keyboard

What is the expected result?

When in 3 step press down button then I got expected result.

What happens instead?

JOSM jumped to Windows list instead sublist in "More".

Please provide any additional information below. Attach a screenshot if possible.

Repository Root: http://josm.openstreetmap.de/svn
Build-Date: 2015-05-25 01:32:15
Last Changed Author: wiktorn
Revision: 8425
Repository UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Relative URL: ^/trunk
URL: http://josm.openstreetmap.de/svn/trunk
Last Changed Date: 2015-05-24 23:41:24 +0200 (Sun, 24 May 2015)
Last Changed Rev: 8425

Identification: JOSM/1.5 (8425 pl) Linux Ubuntu 14.04.2 LTS
Memory Usage: 283 MB / 869 MB (51 MB allocated, but free)
Java version: 1.7.0_79, Oracle Corporation, OpenJDK 64-Bit Server VM
Java package: openjdk-7-jre:amd64-7u79-2.5.5-0ubuntu0.14.04.2
Dataset consistency test: No problems found

Plugins:
- OpeningHoursEditor (30962)
- PicLayer (31114)
- editgpx (30892)
- geotools (31068)
- jts (31002)
- opendata (31116)
- photo_geotagging (30967)
- photoadjust (30964)
- reverter (31120)
- tag2link (31066)
- utilsplugin2 (31120)