Fix libre office connection and other progress dialogs

[Siedlerchr]

Fixes #6477

Error was introduced in #6443 with the ProgressDialog showAndWait
I had to revert that. @btut
The showAndWait broke all dialogs which used the dialog. (E.g). also copy linked files)

• Change in CHANGELOG.md described (if applicable)
• Tests created for changes (if applicable)
• Manually tested changed features in running JabRef (always required)
• Screenshots added in PR description (for UI changes)
• Checked documentation: Is the information available and up to date? If not created an issue at https://github.com/JabRef/user-documentation/issues or, even better, submitted a pull request to the documentation repository.

[btut]

Uh I forgot to roll that back. The ProgressDialog is not actually used by the background-task functionality because I could not get it to work.
I think it would be better to change the name of the method to showProgressDialog. The old name, showProgressDialogAndWait, suggests that the dialog is waited for.

[Siedlerchr]

Indeed, good idea. I renamed it now

[calixtus]

Do I get that right, that most of the progress dialogs can probably be converted to be displayed in the new progress popup?

[btut]

I don't know which other features use the progress dialogue.
I had three problems with the progress dialogue:

• It displays the progress of an actual task. I wanted to show a list of tasks
• It is not waited for
• There is no way to close it when the progress reached 100%

In the dialogue that I implemented as a solution for this, I used the list of tasks stored in StateManager. It would be easy to pass a list of tasks instead. Then we could add an option to the dialogue to only show and it could replace the other dialogues.

But as the original dialogue is not waited for, I guess it is only used as information to the user. How about registering the relevant task in the background-task list in StateManager? Then you could just pop up the new dialogue. You could even pop up the pop-over of the task-progress-indicator in the toolbar. This would be very similar to a show-only dialog (no wait). The user can hide it and check the status later by clicking on the progress-indicator again.

IMO this would be a good way to go. I think the new dialogue and pop-over are more informative as they show the actual progress of tasks if available. AFAICT from the code the old dialogue just showed an indeterminate progress bar.

[btut]

... I just checked and it is just the WaitForSaveFinished dialog that creates a task for this purpose. The other times the dialogue is shown it is shown with actual worker tasks, so progress should be shown.

[tobiasdiez]

I agree these progress dialogs can be replaced by using the new progress popup. None of them actually has a reason to block the UI and can safely be run in the background in my opinion.

[Siedlerchr]

The only critical application is indeed the connection to LibreOffie, but that could also be done in a background task because it's usually finished very fast. However, we have to be careful of tasks throwing exceptions.
The copy linked files to folder displays a progress dialog and afterwards the result dialog.
Indeed it doesn't make sense to block the UI with a progress dialog here