KDE 4.12, Konqueror
context menu -> create file -> plaintext -> "testfile" fine -> a file with the name "testfile" is created
context menu -> create file -> plaintext -> "testfile.crt" WTF -> a file with the name "testfile.crt.txt" is created
context menu -> create file -> plaintext -> "testfile.key" WTF -> a file with the name "testfile.key.txt" is created
this is *not* microsoft windows i thought :-(