Locking elements
While designing your publish-work, you might want to lock the position
and size of an element so that it does not get moved accidentally. To
do that, select the element and click on the "lock" tool-button; to unlock click
on the "unlock" tool-button. You also can do locking/unlocking from its
properties window.
The "Lock All" and "Unlock All" tool-button, will lock/unlock all the elements in your design. When you select a locked element, the selection marks become red and go inward as shown.