You are not bothering me. I just have very limitted amount of time so I am implementing what I believe will give you guys biggest bang for the buck type of thing. I almost finished "downloading multiple zooms" yesterday but alas, I fell asleep

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As far as precaching a predefined region that's tricky, first of all because the earth is not flat, but there is math to fix that. The bigger problem is the space requirements. For example, say that at zoom 16 your region requires 16x16 = 256 cells. Let's say each cell is about 20Kb. That gives us a total of 5Mb, not bad. Now, take zoom 17 (same geo area) = 256*4=1024cells=20Mb. And if we continue:
18 = 80Mb
19 = 320Mb
20 = 1.3Gb
You can see this gets big quick!
As far as source goes... I will have to clean it up and maybe then I will share it out - at this point I embarrassed to
This should work fine for Europe you will just have to find your lat/long. And if you wish to precache all of UK then you better get one of those terrabyte drives! I believe it takes several hundred TB to store all VE world data!!!
And finally, the exception/error message you are getting is probably because your internet connection is not very reliable or VE server is slow. I will take a look at making it a little friendlier with the error messages.
Mark