Prevent clicking on view tab when editing a node
See the content lock module:


  Features
  
  
  Concurrent editing:The user gets notified when he tries to
  edit a node, which is edited by someone else. He cant enter the edit
  mode.
  By node type: Configure content_lock to lock only specific
  nodes.
  By format: Configure content_lock to lock only specific input
  formats.
  No losing content by accident: User gets notified, if he
  wants to leave a edit form by abnormal conditions (close
  browser/window/link click). If the user confirms to leave, the edit
  lock gets automatically removed by an ajax call. You can disable this
  behavior in the admin menu.
  No forgotten locks: The user gets notified
  when he forgets to unlock a node. He/she will be asked to click on a
  link to unlock this node.
  Views integration: Show all open locks using
  any filters, as you have a views integration.