In many cases, in the New Tag Window, the data I type in a field exceeds the display field width. It seemed useful to drag the left column wider, to see more of the data in each field (at the trade-off of seeing a bit less of the adjacent view).
BUT, MC "fights" this by ALSO widening the column that has the field names. I don't need that first Tag Window column widened, I just want to see more of the actual data in the second column. But the width of the two columns seems locked together, probably a percentage relationship (of total Tag Window width, column 1 40%, column 2 60% or so).
Experimenting, when I drag MC's left column to twice as wide, the upper Tree does not oddly adjust, I simply see more of each value. But the Tag Window resizes per its percentage relationships, so I see just about ONE more word of text data, while a huge amount of empty space appears in front of each field name. It's frustrating.
Perhaps there are situations where maintaining the relative sizes of the two columns is helpful, though I can't think of any. I see no reason to devote more column width to field names than the actual field names require, and field names tend to be fairly short. Unlike text data, which can be quite long.
I suggest that the Tag Window field name column be fixed in width, allowing the data column to be resized. And/or, limit the field name column's width to the max length of any of the displayed field names. And/or allow the right column's left edge to be resized as desired, just like field column's work now.
(Yes, I know that selecting a Tag Window field will pop the field out to show its full content, but the hope is to read longer data in most fields without actually selecting them one-at-a-time. The alternative of showing the longer field in a view column is often not desirable, because it reduces/removes other columns from the view window, and/or because the view might be showing images rather than columns of text -- that's my situation when using MC to manage my photo library.)