gmc segfault (likely an easy fix)

[Jason Tackaberry <tack dok org>]

gmc (from today's CVS) will segfault if you edit the properties of any
file and click the icon in the Options tab.

Gtk-WARNING **: invalid cast from (NULL) pointer to `GnomeDialog'

Program received signal SIGSEGV, Segmentation fault.
0x80b7925 in icon_sel_callback (button=0x81c61c8, fp_dlg=0x8204590)
    at gnome-file-property-dialog.c:436
436             gtk_container_add(GTK_CONTAINER(GNOME_DIALOG(fp_dlg->dlg)->vbox), icon_sel);
(gdb) bt
#0  0x80b7925 in icon_sel_callback (button=0x81c61c8, fp_dlg=0x8204590)
    at gnome-file-property-dialog.c:436
#1  0x4027a025 in gtk_marshal_NONE__NONE () at gtkmarshal.c:508
#2  0x40240c3d in gtk_handlers_run (handlers=0x81f08f0, signal=0xbfffde6c, 
    object=0x81c61c8, params=0xbfffdeb0, after=0) at gtksignal.c:1877
#3  0x402401d8 in gtk_signal_real_emit (object=0x81c61c8, signal_id=71, 
    params=0xbfffdeb0) at gtksignal.c:1445
#4  0x4023e435 in gtk_signal_emit () at gtksignal.c:228
#5  0x401bb398 in gtk_button_clicked () at gtkbutton.c:282
#6  0x401bc86b in gtk_real_button_released (button=0x81c61c8)
    at gtkbutton.c:842

[ and so on ...]

Jason.