Abandon this project
Its obvious this company does not want to improve the user experience and utility of this product. As it stands TheBrain is a glorified file organizer but it has/had the potential to be much more.
For those looking for a very customizable personal information manager take a look at TiddlyWiki (its free, cross-platform, non-linear, and requires no installation!). See http://tiddlywiki.com/

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Joe commented
If you want to use Tiddlywiki instead of TheBrain one way to make that transition fluid is to use a mindmap visualizing plugin for Tiddlywiki such as this one: http://tiddlytagmindmap.tiddlyspot.com/
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Leonid commented
Well, Tiddlywiki is really great thing, no questions about that! But it can't visualize links of your content. So it can't be a competitor for TheBrain...
Besides, you are a bit too harsh. I use it already for... 10 years, may be? It becomes better. Well, not so fast, as it could (and should!!!), but still...
Sometimes it looks like that they have no programmers at all )) Or even no personnel at all, only one person in marketing... Judging by mobile versions - er... A student? Several students, each one writing 10 lines of code and quitting, so it took YEARS for very basic program? I don't know :)))
But still, they are alive somehow so many years )
And in fact, there is nothing in the market like it.