Unlocks layout panel.
unlock(panel)

type | string, name of the panel

#### Description

This method will unlock the panel previously locked with .lock() method. This method will call w2utils.unlock() to perform the action. The first argument type is the name of the panel. It can be one of the following:

- top
- left
- main
- right
- preview
- bottom

To unlock main panel w2ui['layout'].unlock('main');