I tried, but wasnt splitted, only a new window opened.

And here is a bugreport.
I started a new instance of the program. The second closing was successful. When a closed the first i got this:
Quote:
Problem signature:
Problem Event Name: APPCRASH
Application Name: LED.exe
Application Version: 0.1.0.2
Application Timestamp: 508cf845
Fault Module Name: StackHash_f43c
Fault Module Version: 6.1.7601.17725
Fault Module Timestamp: 4ec49b8f
Exception Code: c0000374
Exception Offset: 000ce6c3
OS Version: 6.1.7601.2.1.0.256.1
Locale ID: 1038
Additional Information 1: f43c
Additional Information 2: f43cac30086ce4e4a9140b7d326fe968
Additional Information 3: 6e39
Additional Information 4: 6e39a5fff671046ba82b536cc84e0a79