Errors on launching the Arduino Editor ("Bad file selected")

Everytime I start Arduino two error messages appear:

  • Processing can only open its own sketches and other files ending in .ino or .pde
  • Failed to open sketch: "/home/myhomedir"

However, at that point I have not selected any files to open yet...

I am using Arch Linux and the arduino-beta 1:1.5.6_r2-2 package as suggested in the ArchWiki.

Any suggestions what might cause these error messages?