Hi, no problem, thanks for the report, again. Seems I need to remove some dust from AmiKit's compression menu as it is LONG time since it was updated.
Yes, it's enough to drag&drop the archive and it gets unzipped in the destination folder automatically.
I tried to compress some files using TGZ-Create and then decompressing the archive using TGZ-Extract and it worked for me. Maybe the Amiga program is not compatible with some special GZ files created with different compressor. Anyway, you can try the drag&drop feature too.
Did you know you can also double-click the archive to show its content? Then you can select the files and drag&drop them somewhere to get them unpacked.
Check out the tutorial videos explaining how to archive or unarchive files in AmiKit:https://www.youtube.com/user/TheAmiKit