This is a two part feature request.
First part; I like how the program allows you to set the initial main GUI window size and it does this easily with the "Get Current" button. Nicely done. What I think would be a good addition to this is the ability to save the column spacing, both currently displayed and those currently not displayed. At the moment, here the main GUI opens much wider than the default column spacing and the columns need to be expanded to fill the area. Would it be possible to save the column spacing?
Second part; I noticed that when you double-click the spacer between columns to expand a column, the column only widens to the widest currently displayed content. Elsewhere the content within the same column may be wider. Would it be possible to widen the column to the widest content regardless of what's currently displayed?