Crash when pressing <Enter> in fullscreen mode

[Former user]

When the program is started in fullscreen mode (with -f switch), pressing Enter to switch to windowed leads to a crash with the following message:

X Error of failed request:  BadValue (integer parameter out of range for operation)
  Major opcode of failed request:  12 (X_ConfigureWindow)
  Value in failed request:  0x0
  Serial number of failed request:  1529
  Current serial number in output stream:  1531

Interestingly, switching back and forth works when program is started normally (in windowed mode), albeit the switch itself takes considerable amount of time for some reason.