[gdm-list] [gdm-2.30] disabled "Languages:", "Keyborad Layout:" and "Sessions:" widgets on greeter panel

[Jacek Migacz <jacekmigacz ncomputing com>]

 I'm running /gui/simple-greeter/test-greeter-panel and sessions 
drop-down is disabled.
While I'm trying to debug sooner or later i getting lost in the forest 
of preprocessor macros.
However I could see he is reading .desktop definitions and "gnome" label 
was visible at some point.
Stracing does'n help me with it as well.

Only traces i have (not not necessarily useful) are:

** (test-greeter-panel:22845): DEBUG: 
"/usr/share/xsessions/guest-restricted.desktop" is hidden or contains 
non-executable TryExec program

** (test-greeter-panel:22845): DEBUG: 
"/usr/share/xsessions/une-guest-restricted.desktop" is hidden or 
contains non-executable TryExec program

** (test-greeter-panel:22845): DEBUG: 
"/usr/share/xsessions/une-efl-guest-restricted.desktop" is hidden or 
contains non-executable TryExec program

Question is why "select widget" is shaded?