Some Dead Keys not supported

[Alexander Roalter <alexander roalter it>]

I’m not sure this is the correct place to report this, but I have the 
following issue with keyboard input in GTK (and this extends to almost 
my entire Linux).

Recently, I installed the german T3 keyboard, which has amongst many 
special characters also some additional dead keys, namely for the comma 
below and the stroke. Comma below is used for typing Romanian (ș≠ş, 
ț≠ţ), the stroke is used for (ħ, ŧ, used in Maltese).

In xterm and basic X programs, this works as expected, but in GTK 
applications, this dead key is simply ignored, so I get an s instead of ș.

There is a definition for the Windows keyboard that also implements the 
T3 keyboard (or rather a subset of it, the T2 keyboard), which uses a 
special dead key sequence for giving access to Level 5-8 of the keyboard 
(under Linux, this is done by pressing AltGr+Shift, so no deadkey needed 
there). Windows-GTK-programs have the same issue. the deadkeys stroke, 
comma below and this special dead key sequence are ignored (and other 
keyboard layouts which also use differing keyboard mappings, such as the 
german NEO layout have similar problems)

What I gathered is that GTK brings its very own keyboard stroke to 
character engine, and apparently simply ignores the dead key sequences 
it doesn't know about.

Is this assumption correct? And is there anything one can do to either 
let X11 do its thing or have GTK learn about the other deadkey 
sequences? (the latter one would help with my Windows-GTK-Problems at 
Work, since thatʹs the only place I have Windows running)

--
Cheers,
Alex