A hint to ExtLib developers:
There is a problem with the link to the font file in the new xsp-mixin.css.css in the ExtLib V 11.
I was able to fix this changing following in the xsp-mixin.css.css :
url(../fonts/glyphicons-halflings-regular.woff)
with
url('/xsp/.ibmxspres/.extlib/responsive/bootstrap-3.2.0-dist/fonts/glyphicons-halflings-regular.woff')
notice quotes and full path instead of relative paths.
When I did this on the fly in the browser it works Ok, however this needs to be fixed in the ExtLib code so generated on the fly xsp-mixin.css.css will have correct value for woff url.