Display/window glitching, making JOSM unusable

[carstenhag]

What steps will reproduce the problem?

1. Open JOSM
2. Click on something that opens a dialog window or a menu
3. JOSM is entirely glitched now, windows appear where they shouldn't

What is the expected result?

JOSM doesn't glitch

What happens instead?

JOSM glitches

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

Had this error since a few months now, but I had not reported it yet.

URL:https://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2019-08-26 08:55:27 +0200 (Mon, 26 Aug 2019)
Build-Date:2019-08-26 06:57:10
Revision:15322
Relative:URL: ^/trunk

Identification: JOSM/1.5 (15322 de) Windows 10 64-Bit
OS Build number: Windows 10 Pro 1809 (17763)
Memory Usage: 872 MB / 1820 MB (250 MB allocated, but free)
Java version: 1.8.0_221-b11, Oracle Corporation, Java HotSpot(TM) 64-Bit Server VM
Screen: \Display0 1920x1200, \Display1 2560x1440
Maximum Screen Size: 2560x1440
VM arguments: [-Djava.security.manager, -Djava.security.policy=file:<java.home>\lib\security\javaws.policy, -DtrustProxy=true, -Djnlpx.home=<java.home>\bin, -Djnlpx.origFilenameArg=.\josm (1).jnlp, -Djnlpx.remove=false, -Djava.util.Arrays.useLegacyMergeSort=true, -Djnlpx.heapsize=NULL,2048m, -Djnlpx.splashport=50410, -Djnlpx.jvm=<java.home>\bin\javaw.exe]
Dataset consistency test: No problems found

Plugins:
+ imagery_offset_db (34908)
+ openqa (1557250801)
+ turnrestrictions (34977)

Tagging presets:
+ https://josm.openstreetmap.de/josmfile?page=Presets/Bus_lanes&zip=1

Last errors/warnings:
- W: Erweiterungen aktualisieren - org.openstreetmap.josm.plugins.PluginHandler$UpdatePluginsMessagePanel[,0,0,0x0,invalid,layout=java.awt.GridBagLayout,alignmentX=0.0,alignmentY=0.0,border=,flags=9,maximumSize=,minimumSize=,preferredSize=]
- W: Ungültige Erweiterungs-Hauptversion '0.1.0' in Erweiterung microdata_scraping
- W: Ungültige Erweiterungs-Hauptversion '0.1.0' in Erweiterung microdata_scraping
- W: No configuration settings found.  Using hardcoded default values for all pools.