Mass tag edit in the tag editor whenever multiple files are selected instead of having to open a new window

To edit the songs from an album - select them then use Tag Editor panel in the main window. No need for mass tag edit dialog, it is for recursive folder actions or to process huge folders that contain a lot of files.

Main window has a different feature set that can be memory expensive. It is because MP3 files can have a lot of garbage inside, or have huge cover image scans, or simply thousands of covers in thousands of files.

To have no problems with huge volumes - mass editor has been made. It processes only a single file at a time, keeps no history and has a simplified feature set.