This issue serves as point to see which dialogs need to be migrated and which need to be converted:
@JabRef/developers please have a look at that list and see if I maybe missed some
Some of the dialogs are very easy to convert and could be nice beginner tasks

• Global Search Results (includes converting SearchWorker to JavaFX Tasks): Global search not available #4096
• SidePanel: OpenOffice Convert OO/LO SidePanel to javafx #4341
• SidePanel: WebSearch
• Import->Append Library Dialog
• Import Inspection (assigned to @tobiasdiez Rework import inspection dialog in JavaFX #4692)
• Connect to shared DB Convert SharedDatabaseConnect Dialog to Javafx #4040
• Edit-> Manage Keywords
• Edit-> Replace String Fix Part of Issue#3861: Edit->Replace String #4227 (Thx to @marisuki )
• Edit-> Set/Clear/Append Rename Fields
• Groups -> Add new Group New Add Group Dialog #2630
• Groups -> Edit Group
• Library-> New Entry Dialog Convert New entry dialog to javafx #4312
• Library-> Edit Strings Convert Strings Dialog to javafx #3735
• Library-> Library properties Convert LibraryProperties to JavaFX #4617
• Quality -> Find Duplicates (broken Threading due to PreviewPanel) Convert DuplicateResolverDialog to javafx #4601
• Quality -> Duplicate bibtex keys (Removed as part of Remove resolve duplicate keys dialog #4696 )
• Quality -> Merge Entries Convert merge entries dialog to JavaFX #4410
• Quality -> Cleanup Entries
• Quality -> Find unlinked files
• Tools ->New sublibrary from Aux file
• Tools -> Writing XMP Data to Entry (Just a simple status? dialog)
• Options -> Setup general fields Completed General Fields Customizer conversion to JavaFX #4346 (Thx to @NorwayMaple)
• Options -> Manage custom imports
• Options -> Manage custom exports
• Options -> Manage external filetype
• Options -> Manage external filetype -> Edit file types Convert ExternalFileTypeEntryEditor to javafx #4885
• Options -> Manage protected Terms (add file is broken due to Threading)
• Options -> Manage content Selectors Fix for #4628 - cant save new content selectors #4658 (Thx to @ricantech )
• Options -> Customize entry types
• Options -> Bibtex Key Patterns
• Push Entries to Application. Related to Options -> Preferences -> External Programs
• Review Changes dialog Rework external changes dialog in JavaFX #4693
• Import from plaintext
• Merge shared entry dialog
• Wait for save dialog Convert "wait for save" dialog to JavaFX #4697

Still need to be converted to MVVM (not a beginner task):

• Options -> Preferences Fix for issue 3861 : Preferences Dialog to javafx #4253