[Xastir] Maps Offline?

[Eldon Brown]

As a Newbie, it is my understanding that; one of the reasons that "Xastir"
is useful and necessary for plotting APRS is that it can access locally
stored maps (that were download while online) making them viewable while
offline.

The  problem (as I see it) I do not know "how to know" which maps (and at
what "zoom level") I have downloaded until it is too late and offline :-(
 What I get is a big RED area for missing map sections.

Note, as a Newbie, I may be using Xastir wrong or lack understanding, and
maybe there is already a solution to this - if so, please help.

I have tried to zoom and pan to as many location that I think I may "need"
while offline, but inevitable I have found that I missed many
maps sections at a different zoom level that I  could use.

Is there a way to shade missing map sections for one (or two) higher zoom
levels above the current displayed level?  If so, I could easily ensure that
I have down loaded the maps that I plan to use while offline.

Thanks,
Eldon - WA0UWH