Fix for issue 12351

[paulamalvarador-commits]

Closes #12351

This PR improves the sizing behavior of the entry-table tooltip when the preview feature is enabled.
Previously, the tooltip became significantly larger than the actual preview content due to missing layout constraints.
The fix adjusts the tooltip container and the PreviewViewer sizing logic so the tooltip now adapts to its preferred size and remains compact.

Steps to test

Open Preferences → Entry preview.

Enable: “Show preview in entry table tooltip”.

Hover over any entry in the main table.

Observe that the tooltip now:

matches the size of the preview content,

no longer grows excessively,

remains readable and compact.

Screenshot

Mandatory checks

• I own the copyright of the code submitted and I license it under the MIT license
• I manually tested my changes in running JabRef (always required)
• [/] I added JUnit tests for changes (if applicable)
• I added screenshots in the PR description (if change is visible to the user)
• I described the change in CHANGELOG.md in a way that is understandable for the average user (if change is visible to the user)
• I checked the user documentation: Is the information available and up to date? If not, I created an issue at https://github.com/JabRef/user-documentation/issues or, even better, I submitted a pull request updating file(s) in https://github.com/JabRef/user-documentation/tree/main/en.

[github-actions]

Hey @paulamalvarador-commits!

Thank you for contributing to JabRef! Your help is truly appreciated ❤️

We have automated checks in place, based on which you will soon get feedback if any of them are failing. In a while, maintainers will also review your contribution. Once that happens, you can go through their comments in the "Files changed" tab and act on them, or reply to the conversation if you have further inputs.

Please re-check our contribution guide in case of any other doubts related to our contribution workflow.

[Siedlerchr]

Why is that deleted? Seems like there is something wrong with your branch/not up to date

[jabref-machine]

The title of the pull request must not start with "Fix for issue xyz". Please use a concise one-line summary that explains what the fix or change actually does. Example of a good title: "Prevent crash when importing malformed BibTeX entries".

[jabref-machine]

Your pull request modified git submodules.

Please follow our FAQ on submodules to fix.