casings doesn't work with multipolygons

[StrangeGirlMurph]

What steps will reproduce the problem?

1. install the "Highway areas" style (​https://github.com/SupaplexOSM/JOSM-area-highway-Style/blob/main/Styles_area-highway-style.mapcss)
2. create some simple multipolygon
3. give it the area:highway=footway and surface=asphalt

What is the expected result?

There should be a grey inner casing like there are with simple areas that are tagged with area:highway=footway and surface=asphalt

What happens instead?

There is no casing.

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

Relative:URL: ^/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2026-03-28 20:28:41 +0100 (Sat, 28 Mar 2026)
Revision:19555
Build-Date:2026-03-29 01:30:57
URL:https://josm.openstreetmap.de/svn/trunk

Identification: JOSM/1.5 (19555 en) Linux NixOS 26.05 (Yarara)
Memory Usage: 318 MB / 3926 MB (25 MB allocated, but free)
Java version: 21.0.10+7-nixos, N/A, OpenJDK 64-Bit Server VM
Look and Feel: com.sun.java.swing.plaf.gtk.GTKLookAndFeel
Screen: :0.0 2256x1504x[Multi depth]@60Hz (scaling 1.00×1.00)
Maximum Screen Size: 2256×1504
Best cursor sizes: 16×16→16×16, 32×32→32×32
Environment variable LANG: en_US.UTF-8
Environment variable LC_ALL: de_DE.UTF-8
System property file.encoding: UTF-8
System property sun.jnu.encoding: UTF-8
Locale info: en_DE
Numbers with default locale: 1234567890 -> 1234567890
Desktop environment: KDE
VM arguments: [--add-exports=java.base/sun.security.action=ALL-UNNAMED, --add-exports=java.desktop/com.sun.imageio.plugins.jpeg=ALL-UNNAMED, --add-exports=java.desktop/com.sun.imageio.spi=ALL-UNNAMED, -Djosm.restart=true, -Djava.net.useSystemProxies=true, -Dawt.useSystemAAFontSettings=gasp]
Dataset consistency test: No problems found

Plugins:
+ Mapillary (1819)
+ buildings_tools (36474)
+ contourmerge (v0.2.2)
+ utilsplugin2 (36497)

Map paint styles:
+ https://raw.githubusercontent.com/tordanik/direction-cones-style/refs/heads/main/direction-cones.mapcss
+ https://josm.openstreetmap.de/josmfile?page=Styles/HighwayAreas&zip=1