Tutorial 21 - Adding a Locus/Overview Map to a QGIS Print Composer

[@the_idealist.]

Helped a lot. Thorough explanation. Thanks!

[@whatilearnttoday5295]

The 5 second text version:
* Set preview to cache.
* Lock layers.
* Layout overview map.
* Add new map.
....
hmmmm not using the overview map feature.... Well that's 2.5mins of my life I won't get back.