Keep global search bar open when keep on top pin is selected

[Siedlerchr]

Closes #13840

I could not get the "Just move the window to the back" thing working. Either the whole application was moved to background or nothing happened. Tried various things

Steps to test

Have library with entries
Open global search dialog
click on pin to keep on top
double click on entry
=> window stays open

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)
• [x 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.

[koppor]

Tried out works.

The second TODO is not working: "Pin on top off: window should behave "normal" w.r.t. JabRef main window (meaning going to the background if main window is activated)"

[Siedlerchr]

The second TODO is not working: "Pin on top off: window should behave "normal" w.r.t. JabRef main window (meaning going to the background if main window is activated)"

This is what I just wrote in the description of the PR..

[trag-bot]

@trag-bot didn't find any issues in the code! ✅✨