No summary written for this paragraph yet.
Source text
Drag a handle to move a boundary. Split cuts a unit at
a line; Merge joins it to the one above.
The vertical rules are column boundaries. Drag one
sideways to change where a column starts, double-click the page to add
one, or use its × to remove it. Moving a column
boundary re-cuts the page, so it resets that page's line boundaries.