Improve find and focus by pid on Windows

I have found when trying to find and focus by pid that determining the window number is not always straight forward.. After opening Chrome the find / focus by pid methods match 11 windows of which the ids change through usage.. http://img341.imageshack.us/img341/6279/chromec.png

As a workaround I have added in some checks to ignore invisible windows @ https://github.com/johnou/sikuli/commit/e3caefd4e3eb0119610ea6d0b42984d5ed8f08f3

Are there any use cases for finding invisible windows, or would you consider pulling in a patch?