Working with eclipse based FB3 can sometimes be very strange. After forcing a reboot on my machine and then restarting FB3, I got the following error message:
Error Loading Project - A problem occurred when opening project (my project name)
. Try quitting and restarting the application. If the problem persists, you might be using an unsupported product version or your project files might be corrupted
Working with the project seemed impossible, Ctrl+T did not return any type and pressing a Class name did not lead to the class code. After some quick Googling and a second look at my file system I found the problem: my .flexProperties was deleted from my file system for some reason. After I added a copy of the file to my project's root, the problem was resolved.