Adding a member to a relation when it is already in a relation moves the selection down

[Stereo]

What steps will reproduce the problem?

1. Create a relation with members foo, bar, baz
2. In the relation panel, select foo on the left. Select object baz on the right.
3. Click the button to add baz to the relation

What is the expected result?

Nothing (or actually a message saying that the member is already in the relation and that you can copy-paste it if you need it twice)

What happens instead?

Selection on the left panel gets moved to foo and bar

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

URL:http://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2016-09-06 00:16:07 +0200 (Tue, 06 Sep 2016)
Build-Date:2016-09-05 22:21:00
Revision:10966
Relative:URL: ^/trunk

Identification: JOSM/1.5 (10966 en_GB) Mac OS X 10.12.1
Memory Usage: 1147 MB / 3641 MB (641 MB allocated, but free)
Java version: 1.8.0_111-b14, Oracle Corporation, Java HotSpot(TM) 64-Bit Server VM
Screen: Display 69731906 1920x1200
Maximum Screen Size: 1920x1200
VM arguments: [-Djava.library.path=/Applications/JOSM.app/Contents/MacOS, -DLibraryDirectory=${HOME}/Library, -DDocumentsDirectory=${HOME}/Documents, -DApplicationSupportDirectory=${HOME}/Library/Application Support, -DCachesDirectory=${HOME}/Library/Caches, -DSandboxEnabled=false, -Dapple.laf.useScreenMenuBar=true, -Dcom.apple.macos.use-file-dialog-packages=true, -Dcom.apple.macos.useScreenMenuBar=true, -Dcom.apple.mrj.application.apple.menu.about.name=JOSM, -Dcom.apple.smallTabs=true, -Dawt.useSystemAAFontSettings=on, -Dswing.aatext=true, -Dsun.java2d.xrender=true

-Dsun.java2d.xrender=true
]
Dataset consistency test: No problems found

Plugins:
+ AddrInterpolation (32699)
+ CommandLine (32796)
+ DirectDownload (32699)
+ DirectUpload (32699)
+ FixAddresses (32796)
+ HouseNumberTaggingTool (32699)
+ ImportImagePlugin (32699)
+ ImproveWay (9)
+ Mapillary (v1.3.1)
+ OSMRecPlugin (32796)
+ OpenStreetView (22)
+ OpeningHoursEditor (32699)
+ PicLayer (32796)
+ RoadSigns (32796)
+ alignways (32921)
+ apache-commons (32699)
+ apache-http (32699)
+ areaselector (282)
+ auto_tools (1471534390)
+ buildings_tools (32944)
+ conflation (0.3.0)
+ contourmerge (1030)
+ download_along (32946)
+ ejml (32680)
+ geotools (33042)
+ gson (32680)
+ imagery-xml-bounds (32699)
+ imagery_offset_db (32796)
+ importvec (32699)
+ jts (32699)
+ livegps (32954)
+ log4j (32699)
+ mapdust (32787)
+ merge-overlap (32699)
+ namemanager (32699)
+ opendata (33040)
+ pdfimport (32796)
+ pt_assistant (32990)
+ public_transport (32796)
+ public_transport_layer (32817)
+ reverter (32796)
+ rex (26)
+ routing (32796)
+ scripting (30761)
+ splinex (32918)
+ surveyor (32796)
+ tageditor (33021)
+ terracer (33031)
+ turnrestrictions (32796)
+ undelete (32699)
+ utilsplugin2 (32815)

Tagging presets:
+ https://josm.openstreetmap.de/josmfile?page=Presets/NewTags&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/BicycleJunction&preset&zip=1
+ http://osmtools.de/josm/steps.xml
+ https://josm.openstreetmap.de/josmfile?page=Presets/Historic_Stone&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/LaneAttributes&preset&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/Towers&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/Golf_Course&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/PublicTransportOneClick&zip=1

Map paint styles:
- https://josm.openstreetmap.de/josmfile?page=Styles/Lit&style&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/ParkingLanes&style&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Surface&style&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Maxspeed&style&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Modified&style&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/LessObtrusiveNodes&style&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/AddressValidator&style&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Noname&style&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Power&style&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Surface-DataEntry&style&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/PowerMapping&style&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Lane_and_Road_Attributes&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/BesideTheRoad_Speed&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/TreeCrownDiameter&style&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/SlovakiaBicycleRoutes&style&zip=1
- https://github.com/simon04/coloured-addresses.mapcss/raw/master/dist/coloured-addresses.mapcss
- https://josm.openstreetmap.de/josmfile?page=Styles/Coloured_Streets&style&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Coloured_Suburb&style&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Cycleways&style&zip=1
- http://maps.openstreetmap.ie/josm/townland.mapcss
- https://josm.openstreetmap.de/josmfile?page=Styles/SlovakiaBicycleRoutes&style&zip=1
- https://github.com/GlassOceanos/indoor-JOSM-style/archive/master.zip
- https://josm.openstreetmap.de/josmfile?page=Styles/PublicTransport&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/PTStops&zip=1

Last errors/warnings:
- W: Old style SideButton usage for action org.openstreetmap.josm.plugins.mapillary.gui.MapillaryChangesetDialog$SubmitAction@25862f5a
- W: java.net.SocketTimeoutException: Read timed out
- E: java.net.SocketTimeoutException: Read timed out
- E: org.openstreetmap.josm.io.OsmTransferException: Could not connect to the OSM server. Please check your internet connection.. Cause: java.net.SocketTimeoutException: Read timed out
- E: IO Exception - <html>Failed to upload data to or download data from<br>'https://api.openstreetmap.org/api/0.6/relation/2744515/history'<br>due to a problem with transferring data.<br>Details (untranslated): Read timed out</html>
- W: java.net.SocketTimeoutException: Read timed out
- W: Already here java.net.SocketTimeoutException: Read timed out
- E: java.net.SocketTimeoutException: Read timed out
- E: org.openstreetmap.josm.io.OsmTransferException: Could not connect to the OSM server. Please check your internet connection.. Cause: java.net.SocketTimeoutException: Read timed out
- E: IO Exception - <html>Failed to upload data to or download data from<br>'https://api.openstreetmap.org/api/0.6/relation/2744515/history'<br>due to a problem with transferring data.<br>Details (untranslated): Read timed out</html>

[Stereo]

After