Why STS removes application generated directories?

[vw729]

When I first noticed that our application generated directories were disappeared at STS, I thought that STS cleaned up the installation directory for a re-installation. Today, when I was working on a related application functionality, I just recognized that STS removes our application generated directories about every time when it publishes a updated file to the TC without re-installation. Why STS does that?

[vw729]

If that is how STS keeps the installation clear, is a way to configuration the behavior? It is very annoying that all uploaded image files get removed each time when a JSP file is updated during the development phase.