Fit a column to its names

In Column view, double-click a column's resize handle. In List view, double-click the divider in the column header.

How to do it

1. In Column view, double-click the resize handle at the bottom of a column: it fits the names inside it.
2. Right-click the handle for Right Size This Column, Right Size All Columns Individually and Right Size All Columns Equally.
3. In List view, double-click the divider to the right of a column header to fit that column, as in Finder.

More detail in the guide: Browsing files