The column headers at the top of the document can be used to change the width of the columns. To resize a column, drag the right edge of the corresponding header button. To restore a column's default width, double-click the right edge of its header button.
For example, to resize the Name column, position the cursor over the right edge of the Name header button. The cursor changes to a divider with horizontal arrows. Now left-click, and while holding down the left mouse button, move the cursor horizontally.
The result depends on the "Show window contents while dragging" system setting (Control Panel/Display/Effects). If this property is checked, the column stretches or shrinks, and columns to the right of it move. If this property is unchecked, the column width doesn't change until you release the left mouse button; while you drag, a vertical line moves over the document, indicating the column's right edge.
Note that if "Show window contents while dragging" is checked, resizing a column requires drawing a large number of controls repeatedly; this can cause temporary screen anomalies, and may result in excessive CPU usage.
It's possible to make a column disappear entirely, by dragging it all the way to the left. To restore it, go to the right edge of the preceding column's header button, and position the cursor slightly to the right of that point. The cursor changes to a double divider with horizontal arrows. Now left-click and drag to the right, and the missing column reappears.
The column headers are also used for sorting tracks.