Keyboard shortcuts (specifically for delete and undo) stop working after switching apps (at least under Mac OS)

[chris@…]

What steps will reproduce the problem?

1. Be in an edit session in JOSM
2. Switch to another app (either command+tab or by using control+arrows to change space/desktop or fullscreen apps)
3. Go back to JOSM
4. Try to undo a change with command+Z or delete an object with the delete key

What is the expected result?

The change is undone or the object is deleted

What happens instead?

Nothing

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

This gives me a suspicion that's it's a problem with Java UI frameworks playing nicely under Mac OS. It is similar to the problem where closing certain dialogues (I've personally noticed it on the download area and F3 preset selection) blocks keyboard shortcuts from working at all until you open and close another dialogue box.

URL:http://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2017-12-31 03:09:43 +0100 (Sun, 31 Dec 2017)
Build-Date:2017-12-31 02:33:46
Revision:13265
Relative:URL: ^/trunk

Identification: JOSM/1.5 (13265 en) Mac OS X 10.11.6
OS Build number: Mac OS X 10.11.6 (15G18013)
Memory Usage: 640 MB / 1820 MB (419 MB allocated, but free)
Java version: 1.8.0_151-b12, Oracle Corporation, Java HotSpot(TM) 64-Bit Server VM
Screen: Display 2026427093 1920x1080
Maximum Screen Size: 1920x1080
VM arguments: [-Djava.security.policy=file:<java.home>/lib/security/javaws.policy, -DtrustProxy=true, -Djnlpx.home=<java.home>/bin, -Djava.security.manager, -Djnlpx.origFilenameArg=${HOME}/Library/Application Support/Oracle/Java/Deployment/cache/6.0/56/1ee8cfb8-668392a0, -Djnlpx.remove=false, -Dsun.awt.warmup=true, -Djava.util.Arrays.useLegacyMergeSort=true, -Dmacosx.jnlpx.dock.name=JOSM, -Dmacosx.jnlpx.dock.icon=${HOME}/Library/Application Support/Oracle/Java/Deployment/cache/6.0/16/47ee53d0-5050928a.icns, -Djnlp.application.href=https://josm.openstreetmap.de/download/josm.jnlp , -Djnlpx.jvm="<java.home>/bin/java"]
Dataset consistency test: No problems found

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.net.UnknownHostException: ecn.t1.tiles.virtualearth.net
- W: java.net.UnknownHostException: ecn.t1.tiles.virtualearth.net
- W: java.net.UnknownHostException: ecn.t1.tiles.virtualearth.net
- W: java.net.UnknownHostException: ecn.t1.tiles.virtualearth.net
- W: java.net.ConnectException: Network is down (connect failed)
- E: java.net.ConnectException: Network is down (connect failed)
- W: org.openstreetmap.josm.io.OsmTransferException: Could not connect to the OSM server. Please check your internet connection.. Cause: java.net.ConnectException: Network is down (connect failed)