Locks popup window.
lock(message, [showSpinner])

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

#### Description

This method will lock the popup by added a semi-transparent div on top of popup content. The user will not be able to interact with the popup or its content until the popup is unlocked with .unlock(). This method will call w2utils.lock() to perform the locking. You have 3 options how you want to lock the content.
Lock with a message and a spinner: w2popup.lock('Loading...', true); Lock w/o a message, but with a spinner: w2popup.lock('', true); Lock w/o a message and w/o a spinner: w2popup.lock('');