When you start typing and no file is selected

[ohrenkino]

see e.g. here:

[X] Launching MP3Tag with file does not automatically select it

Consider the following scenario: You open a file or folder via the context menu integration in Explorer. The first file is now shown with a dashed focus rectangle, but its tags are not loaded automatically into the panel on the left hand side. So if you start editing the properties in the panel, you can actually not save them, and as soon as you click on the file in the right hand panel, the edited tags are lost. There are two possible solutions: Grey out the left panel, just like the save bu…

or here:

Enhancement: Disable controls in left panel when 0 selected files

So you can't set an album cover or key in something that will not be saved/lost!