My system of downloading is that I have
eg.
d:\dl\math
d:\dl\science
...

Then I have
d:\dl\math\project1
d:\dl\math\project2
...

When I type in the folder name in the "base path" combo 
box, for example "d:\dl\math"
an empty hts-cache is formed in that directory, which is 
not necessary, because it is not a real project. Later on, 
after it is finished with downloading, it will ask if I 
want to delete the empty hts-cache.