Scroll wheel behavior on Tag Panel

Some versions back, I reported on a problem that occurred when using the mouse wheel while working in the Tag Panel. Sometimes, rolling the wheel when the pointer overlays a field's value, the value would change from the previously entered (and already written) text to <blank>. This behavior easily goes unnoticed, which is a serious issue.. The result is that further tag panel operations end up removing desired values from the affected field(s).

The problem was promptly fixed after I first reported it, but it appears that it has crept back into the code. It's the only way I can explain the fact that once-written tags disappear mysteriously, causing us to either (1) unknowingly omit critical metadata at completion, or (2) re-entering the tag field's values all over again.

Please make sure the mouse wheel is disabled when the pointer is in the body of the tag panel. Of course it would be nice if it still operates when the pointer is in the scroll bar region.

There is a difference between Mp3tag having the focus on a certain field on the Tag Panel and having the focus on the Tag Panel itself.

The former also enables the scroll wheel to switch between entries in the drop-down list. This is standard behavior on Windows. It's deactivated once the user starts editing in one field (as described by @JJ_Johnson's suggestion in [F] Tag Panel problems with 'wheel mouse').

The latter simply scrolls the whole Tag Panel (in case a scroll bar is visible). Further experiments with @ohrenkino in a private conversation have shown that this is only possible, if the Windows 10 setting "Scroll inactive windows when I hover of them" is enabled.