Inconsistent filter behaviour between normal and locked layers

[Don-vip]

What steps will reproduce the problem?

1. Have a normal OSM data layer and a filter enabled
2. Close the filter dialog
3. Note that filtering is disabled when the dialog is closed
4. Do the same with a locked layer

What is the expected result?

Filtering should behave as for normal layers (i.e: disabled)

What happens instead?

Filtering is still enabled

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

Build-Date:2019-04-14 22:31:25
Revision:14987
Is-Local-Build:true

Identification: JOSM/1.5 (14987 SVN en) Windows 10 64-Bit
OS Build number: Windows 10 Pro 1803 (17134)
Memory Usage: 1407 MB / 3634 MB (933 MB allocated, but free)
Java version: 1.8.0_202-b08, AdoptOpenJdk, OpenJDK 64-Bit Server VM
Screen: \Display0 1920x1080, \Display1 1920x1080
Maximum Screen Size: 1920x1080
VM arguments: [-ea, -Dfile.encoding=UTF-8]
Program arguments: [--debug]
Dataset consistency test: No problems found

Plugins:
+ apache-commons (34908)
+ ejml (34908)
+ geotools (34908)
+ jaxb (34908)
+ jts (34908)
+ junctionchecking (34977)
+ log4j (34908)
+ opendata (34977)
+ tag2link (34977)
+ utilsplugin2 (34977)

Last errors/warnings:
- W: No configuration settings found.  Using hardcoded default values for all pools.

[Don-vip]

In 14992/josm:

fix #17610 - make filter model aware of locked layers