Add information for Timeline plugin when no time dimension layer is selected in TOC #11959

[rowheat02]

Description

Currently, if none of the time-enabled layers are hidden in the TOC, the timeline is not shown. But when there are two time-enabled layers and the selected one is disabled from the TOC. The snapping layer is still the previously selected one and it seems confusing. So now a warning icon with a tooltip is shown in such a case.

Please check if the PR fulfills these requirements

• The commit message follows our guidelines: https://github.com/geosolutions-it/MapStore2/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

What kind of change does this PR introduce? (check one with "x", remove the others)

• Enhancement

Issue

fixes #11959(gitub is not letting me link issue using Developement, so using keyword "fixes" to link the issue)
What is the current behavior?

No warning when a hidden layer on the TOC is the selected layer in the timeline

What is the new behavior?

Warning shown when a hidden layer is the selected layer in the timeline.

Breaking change

Does this PR introduce a breaking change? (check one with "x", remove the other)

• Yes, and I documented them in migration notes
• No

Other useful information

[offtherailz]

• The issue description is obsolete please update
• Please fix the translations (this is not referring to anything, the guide layer)

[offtherailz]

Successfully created backport PR for 2026.02.xx:

• [Backport 2026.02.xx] Add information for Timeline plugin when no time dimension layer is selected in TOC #11959 #12839

[ElenaGallo]

@rowheat02 When the guide layer is selected again in the TOC, it becomes visible again in the timeline but a warning appears in the TOC saying that the layer was not loaded correctly.

timeline-issue.mp4

Regarding this point mentioned in the issue: #11959 (comment)
Could you please confirm whether it was decided to remove the Show/Hide Timeline button?

[rowheat02]

Hi @ElenaGallo

@rowheat02 When the guide layer is selected again in the TOC, it becomes visible again in the timeline but a warning appears in the TOC saying that the layer was not loaded correctly.

In TOC, since the current time was applied from another layer(Meteorite...), so on that timestamp data may not be available for Boxes_with_time. If you select again box_with_time on timeline then it must work. So this behaviour is normal.

Screen.Recording.2026-09-22.at.14.15.22.mov

Regarding this point mentioned in the issue: #11959 (comment)
Could you please confirm whether it was decided to remove the Show/Hide Timeline button?

That comment was outdated.
That button was removed during this issue: #11926