Insert > File > Child Document won't work for filenames with spaces

[Bennett Helm]

For LyX-1.5svn, attempting to insert a child document whose filename  
has spaces results in only the first word of the filename being used,  
and so the file is not found.

I just reported this as bug # 3135:
<http://bugzilla.lyx.org/show_bug.cgi?id=3135>

Bennett