Reorder Imagery menu item turns into open list of all layers when added to toolbar.

[InsertUser]

What steps will reproduce the problem?

1. Open preferences > Toolbar customisation
2. Expand the Imagery folder of the actions list and drag Reorder Imagery Layers to the toolbar column (alternately use the '<' button, the same result is obtained)
3. Close the Preferences window.
4. Click the new toolbar button.

What is the expected result?

Imagery should cycle, as happens when clicking the menu item, or using the shortcut.

What happens instead?

The Layers dialogue disappears.

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

Note that while the preferences dialog refers to this as "Reorder imagery layers" while creating the shortcut, when re-opened it simply says "Layers".

The mouseover text for the resulting button says "Open a list of all loaded layers _{(Alt+Shift+L)}" rather than the expected "Reorders non-overlay imagery layers _{(Back Quote)}".

Might this be something to do with both functions sharing the same icon as the layers panel shortcut on the edit toolbar?

URL:https://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2019-06-03 00:05:30 +0200 (Mon, 03 Jun 2019)
Build-Date:2019-06-02 22:10:24
Revision:15155
Relative:URL: ^/trunk

Identification: JOSM/1.5 (15155 en_GB) Windows 10 64-Bit
OS Build number: Windows 10 Pro 1903 (18362)
Memory Usage: 1514 MB / 1820 MB (561 MB allocated, but free)
Java version: 1.8.0_181-b13, Oracle Corporation, Java HotSpot(TM) 64-Bit Server VM
Screen: \Display0 2560x1440
Maximum Screen Size: 2560x1440
Dataset consistency test: No problems found

Plugins:
+ AddrInterpolation (34908)
+ CustomizePublicTransportStop (${version.entry.commit.revision})
+ FastDraw (34977)
+ ImportImagePlugin (34908)
+ Mapillary (1.5.18)
+ OpenStreetCam (236)
+ OpeningHoursEditor (34977)
+ RoadSigns (${version.entry.commit.revision})
+ SeaChart (34970)
+ SeaMapEditor (34908)
+ apache-commons (34908)
+ apache-http (34908)
+ auto_tools (73)
+ buildings_tools (34982)
+ changeset-viewer (22)
+ conflation (0.6.3)
+ continuosDownload (82)
+ editgpx (34908)
+ ejml (34908)
+ geotools (34908)
+ graphview (34977)
+ jaxb (35014)
+ jna (34908)
+ jogl (1.2.3)
+ jts (34908)
+ kendzi3d (1.0.205)
+ kendzi3d-resources (0.0.2)
+ log4j (34908)
+ measurement (34977)
+ opendata (34997)
+ pt_assistant (705)
+ reverter (34999)
+ rex (53)
+ tageditor (34977)
+ terracer (34977)
+ turnlanes (34994)
+ turnlanes-tagging (281)
+ turnrestrictions (34977)
+ undelete (34977)
+ utilsplugin2 (34977)
+ waydownloader (34977)

Tagging presets:
+ https://raw.githubusercontent.com/yopaseopor/traffic_signs_preset_JOSM/master/GB.zip
+ https://josm.openstreetmap.de/josmfile?page=Presets/Golf_Course&zip=1
+ https://raw.githubusercontent.com/OpenNauticalChart/josm/master/Presets_Hafen.xml
+ https://josm.openstreetmap.de/josmfile?page=Presets/Diving&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/OpenSeaMap-PresetForSeamarks&zip=1
+ https://raw.githubusercontent.com/OpenSeaMap/josm/master/Presets_Sport.xml
+ https://raw.githubusercontent.com/OpenNauticalChart/josm/master/INT-1-preset.xml
+ https://josm.openstreetmap.de/josmfile?page=Presets/BuildingPreset&zip=1
+ https://raw.githubusercontent.com/species/josm-preset-wheelchair/master/sidewalks_kerbs.xml
+ http://zibi.openstreetmap.org.pl/kendzi/k/Simple3dPreset/s3db-preset.zip

Map paint styles:
- https://raw.githubusercontent.com/OpenSeaMap/josm/master/INT1_Seamark.mapcss
- https://raw.githubusercontent.com/OpenSidewalks/OpenSidewalks-Schema/master/open_sidewalks.mapcss
- https://josm.openstreetmap.de/josmfile?page=Styles/Sidewalks&zip=1
- https://raw.githubusercontent.com/yopaseopor/traffic_signs_style_JOSM/master/Styles_Traffic_signs_EUR.zip
- https://josm.openstreetmap.de/josmfile?page=Styles/Ph_Typhoon&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Modified&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Historic_Stones&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/SimpleBuildingTags&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/SimpleRoofTags&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Lane_and_Road_Attributes&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Lane_features&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Lane_features_ryg&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/PublicTransport&zip=1

Validator rules:
+ https://raw.githubusercontent.com/OpenNauticalChart/josm/master/Seamark.validator.mapcss

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

[Don-vip]

In 15207/josm:

fix #17826 - use a proper icon for "reorder imagery layers" action