The Levels Menu

In CPSokoban, you can tackle the levels in any order you like. Because of this, and so you have a chance to save your solution to an external file, the level will not change automatically when you solve a level; you must change it yourself.

Levels->Next level (N)
Go to the next level in the current set.
Levels->Previous level (P)
Go to the previous level in the current set.
Levels->Next unsolved (Space)
Go to the first level after the current one that has not been solved.
Levels->First unsolved (F)
Go to the first level in the current set that has not been solved.
Levels->Go to (G)
Brings up a dialog that lets you choose any level in the current set.