Editing layouts privilegescan limit access to in a file. For a file, you can set:•Privileges for all layouts: you can allow or prohibit the ability to switch to and make design changes to all layouts. You can also prohibit access to all layouts in a file.•Custom privileges for individual layouts: you can set two types of access limits for each layout:•Design and view limits for each layout: whether the privilege set permits making design changes to a layout in Layout mode, view-only layout access, or no layout access at all.•Data access limits for each layout: whether the privilege set permits accessing, viewing, or modifying data displayed by each layout. When access to data is prohibited, the user can view the layout but will see <No Access> instead of any field data.
Show Custom Dialog can specify an input field formatted with bullets instead of echoing the user's input. This can be set up as a "sort of" password--it's not necessarily a password defined in manage security.
But if you take DavidAnder's advice, you shouldn't need to use this option as the data on the file tab can be kept unaccessible via privilege settings in manage security and possibly with a script that checks the user's privilege set.