xffm crashes when selecting certain files. In my case file named '-M'
gdb output:
gdb xffm
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This GDB was configured as "i386-pc-linux-gnu"...(no debugging symbols
found)...Using host libthread_db library "/lib/libthread_db.so.1".

(gdb) run
Starting program: /usr/bin/xffm 
warning: Unable to find dynamic linker breakpoint function.
GDB will be unable to debug shared library initializers
and track explicitly loaded dynamic code.
(no debugging symbols found)...(no debugging symbols found)...(no debugging
symbols found)...(no debugging symbols found)...(no debugging symbols
found)...(no debugging symbols found)...
(no debugging symbols found)...(no debugging symbols found)...(no debugging
symbols found)...(no debugging symbols found)...(no debugging symbols
found)...(no debugging symbols found)...
(no debugging symbols found)...(no debugging symbols found)...(no debugging
symbols found)...(no debugging symbols found)...(no debugging symbols
found)...(no debugging symbols found)...
(no debugging symbols found)...(no debugging symbols found)...(no debugging
symbols found)...(no debugging symbols found)...(no debugging symbols
found)...(no debugging symbols found)...
(no debugging symbols found)...(no debugging symbols found)...(no debugging
symbols found)...(no debugging symbols found)...(no debugging symbols
found)...[Thread debugging using libthread_db enabled]
[New Thread 16384 (LWP 12134)]

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 16384 (LWP 12134)]
0x4082180f in mallopt () from /lib/libc.so.6
(gdb) bt
#0  0x4082180f in mallopt () from /lib/libc.so.6
#1  0x4082060d in free () from /lib/libc.so.6
#2  0x405d9b23 in g_free () from /usr/lib/libglib-2.0.so.0
#3  0x084a19e9 in ?? ()
#4  0x4002e1ec in ?? () from /usr/lib/libxffm.so.0
#5  0x4002e1ec in ?? () from /usr/lib/libxffm.so.0
#6  0x40026017 in reg_duplicate_app () from /usr/lib/libxffm.so.0
#7  0x084a19e9 in ?? ()

I would assume that whenever selecting a file starting with - (dash) it crashes.