I have a problem with some non-native mac software (Perforce Diff and Kdiff3).
When I use the Open File Dialog, I can see the hidden files, but I can not select them or interact with them at all.
In contrast, when using the native Mac TextEdit, when I use the Open File Dialog, I can see and open the hidden files.
This is a screenshot of the Kdiff3 Open File Dialog. I can see the hidden files, but I can not select them.
OS X version 10.10.3 Yosemite.
I did this to make Finder show hidden files
defaults write com.apple.finder AppleShowAllFiles YES
I did this to make the file open dialog show hidden files
defaults write -g AppleShowAllFiles -bool true
Best Answer
You can often alt/option click on files to force open them.