JOSM freezes after showing popup for unsuccesfull search

[GerdP]

What steps will reproduce the problem?

1. Load some data
2. Search for an object that doesn't exist, e.g. highway=xyz
3. A popoup is shown that nothing was found
4. Sometimes this popup disappears when I press Enter or Esc, sometimes not. I decided to open a ticket

and while reproducing the problem JOSM decided to freeze.

What is the expected result?

Popup should disappear

What happens instead?

In this particular case JOSM no longer reacts. I cannot close the popup by pressing Enter or Esc or by clicking on the OK button. When I click somewere else I hear a Windows System Sound.
Pressing Alt+F4 also doesn't work.

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: 2017-07-31 01:02:55 +0200 (Mon, 31 Jul 2017)
Build-Date:2017-07-31 01:53:17
Revision:12545
Relative:URL: ^/trunk

Identification: JOSM/1.5 (12545 de) Windows 10 64-Bit
OS Build number: Windows 10 Home 1703 (15063)
Memory Usage: 2666 MB / 5461 MB (1344 MB allocated, but free)
Java version: 1.8.0_121-b13, Oracle Corporation, Java HotSpot(TM) 64-Bit Server VM
Screen: \Display0 1920x1080
Maximum Screen Size: 1920x1080
Dataset consistency test: No problems found

Plugins:
+ OpeningHoursEditor (33185)
+ apache-commons (32994)
+ buildings_tools (33004)
+ ejml (32680)
+ geotools (33380)
+ jts (32699)
+ o5m (33243)
+ opendata (33438)
+ pbf (33241)
+ poly (33004)
+ reverter (33088)
+ utilsplugin2 (33328)

Last errors/warnings:
- W: java.io.IOException: Attribution is not loaded yet
- W: java.io.IOException: Attribution is not loaded yet
- W: java.io.IOException: Attribution is not loaded yet
- W: java.io.IOException: Attribution is not loaded yet
- W: java.io.IOException: Attribution is not loaded yet
- W: java.io.IOException: Attribution is not loaded yet
- W: java.io.IOException: Attribution is not loaded yet
- W: java.io.IOException: Attribution is not loaded yet
- W: java.io.IOException: Attribution is not loaded yet
- W: java.io.IOException: Attribution is not loaded yet

[GerdP]

visual vm threaddump