Position of zoom slider not correctly initialised after opening session file

[Adrian]

What steps will reproduce the problem?

1. Launch JOSM, or delete all layers if JOSM is already running.
2. Load this session file.
3. Begin to drag the zoom slider.

What is the expected result?

The zoom level changes in small steps.

What happens instead?

The zoom level jumps by a large amount. This happens because JOSM did not place the zoom slider in the correct position after opening the session file.

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

I fixed a related problem in #15039. That fix may give a clue about where to start looking in the JOSM code. The issue in that case was that a listener had been inadvertently disconnected.

4. Press 8 to go back to what the view was after opening the session file.
5. Open the session file again.

What is the expected result?

The view remains the same.

What happens instead?

The view changes.

Relative:URL: ^/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2022-10-31 17:29:20 +0100 (Mon, 31 Oct 2022)
Revision:18583
Build-Date:2022-11-01 02:30:58
URL:https://josm.openstreetmap.de/svn/trunk

Identification: JOSM/1.5 (18583 en_GB) Mac OS X 11.7
OS Build number: macOS 11.7 (20G817)
Memory Usage: 416 MB / 4096 MB (268 MB allocated, but free)
Java version: 18.0.2.1+1, Azul Systems, Inc., OpenJDK 64-Bit Server VM
Look and Feel: com.apple.laf.AquaLookAndFeel
Screen: Display 725375437 1920×1200 (scaling 1.00×1.00)
Maximum Screen Size: 1920×1200
Best cursor sizes: 16×16→16×16, 32×32→32×32
Environment variable LANG: en_GB.UTF-8
System property file.encoding: UTF-8
System property sun.jnu.encoding: UTF-8
Locale info: en_GB
Numbers with default locale: 1234567890 -> 1234567890

Plugins:
+ ImportImagePlugin (36013)
+ InfoMode (35978)
+ PicLayer (1.0.2)
+ apache-commons (36003)
+ cadastre-fr (36021)
+ editgpx (35931)
+ ejml (35924)
+ geotools (36028)
+ http2 (35921)
+ imagery_offset_db (35978)
+ jackson (36006)
+ jaxb (35952)
+ jts (36004)
+ log4j (36007)
+ measurement (35978)
+ opendata (36025)
+ photo_geotagging (35933)
+ poly (35976)
+ reverter (36011)
+ turnrestrictions (36011)
+ undelete (36011)
+ utilsplugin2 (36011)
+ waydownloader (36011)

Last errors/warnings:
- 00009.351 W: Update plug-ins - Last plug-in update more than 39 days ago.