Unreadable text with light-on-dark system theme

[arvid.nr+josm@…]

What steps will reproduce the problem?

1. Use Linux
2. Set JOSM to use GTK+ "Look and feel" (Preferences -> Display Settings -> Look and Feel)
3. Use a GTK+ theme with light text and dark background.
4. Use imagery that triggers message "Aerial Imagery ... might be misaligned".
5. Observe unreadable text

What is the expected result?

The text should either be readable, or the background color in question should be configurable in Preferences -> Display Settings -> Colors

What happens instead?

I have not been able to find a place where I can configure said background color, though I may be missing it, since the colors are sometimes really hard to read in the list in preferences (light on light).

See attached screen shot.

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: 2015-12-30 03:21:52 +0100 (Wed, 30 Dec 2015)
Build-Date:2015-12-30 02:34:43
Revision:9220
Relative:URL: ^/trunk

Identification: JOSM/1.5 (9220 en) Linux Debian GNU/Linux 8.2 (jessie)
Memory Usage: 874 MB / 3568 MB (591 MB allocated, but free)
Java version: 1.8.0_66-internal, Oracle Corporation, OpenJDK 64-Bit Server VM
VM arguments: [-Djosm.restart=true, -Djosm.home=/home/arvid/.josm-latest, -Djava.net.useSystemProxies=true]
Dataset consistency test: No problems found

Plugins:
- AddrInterpolation (31772)
- CommandLine (31869)
- HouseNumberTaggingTool (31772)
- OpeningHoursEditor (31772)
- PicLayer (31772)
- RoadSigns (31772)
- alignways (31772)
- apache-commons (31772)
- buildings_tools (31772)
- download_along (31772)
- ejml (31772)
- ext_tools (31772)
- geotools (31774)
- gpsblam (31772)
- gpxfilter (31772)
- graphview (31772)
- imagery_offset_db (31772)
- jts (31772)
- log4j (31879)
- measurement (31772)
- opendata (31772)
- routing (31772)
- terracer (31772)
- turnlanes (31772)
- turnrestrictions (31772)
- utilsplugin2 (31772)
- waydownloader (31772)

Last errors/warnings:
- W: Cannot start IPv4 remotecontrol https server on port 8112: Keystore was tampered with, or password was incorrect
- W: Cannot start IPv6 remotecontrol https server on port 8112: Keystore was tampered with, or password was incorrect

[arvid.nr+josm@…]

Screenshot of problem