The internal function mousetrap_get_next_id starts at the first number after the last reserved identifier(MT_RESERVED_LAST) in this enum. If you wish to use your own identifier generation scheme, identifiers less than or equal to MT_RESERVED_LAST will cause undesirable results.
|MT_TRANSPARENCY||Used to denote transparency information in a mousetrap.|
|MT_PLACEHOLDER||Used for arbitrary things. Mostly internal, but also a failure value from mousetrap_lookup_id.|
|MT_RESERVED_LAST||Included to make client code work easily when/if more reserved IDs are added to the system.|