Locks layout panel.
lock(panel, message, [showSpinner])

message | string, message
showSpinner | boolean, optional, spinner indicator

#### Description

This method will lock the panel by added a semi-transparent div on top of popup content. The user will not be able to interact with the panel or its content until the panel is unlocked with .unlock(). This method will call w2utils.lock() to perform the locking. The first argument type is the name of the panel. It can be one of the following:

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

You have 3 options how you want to lock the content. Lock with a message and a spinner: w2layout.lock('main', 'Loading...', true); Lock w/o a message, but with a spinner: w2layout.lock('main', '', true); Lock w/o a message and w/o a spinner: w2ui['layout'].lock('main');