[pstricks] Problem with psframe and boxsep=false

[ARno]

I have a problem with this code:

\begin{pspicture}(0,-0.4675)(1.54,0.4675)
\definecolor{color5b}{rgb}{0.4,0.6,1.0}
\usefont{T1}{ptm}{m}{n}
\rput(0.7825,-0.0125){\psframebox[linewidth=0.04,framesep=0.02,
boxsep=false]{a\psframebox[linewidth=0.04,fillstyle=solid,
fillcolor=color5b,framesep=0.26,boxsep=false]{bcdef}gh}}
\end{pspicture}

the letter 'a' of the first box is hidden by the second box, but 'gh' of 
the first box is not hidden by the second box. Why ?
If an answer is that the 'a' is displayed before the second box, so it 
is hidden by it, I think it is not logic: if a part of  the text of a 
box is hidden, all the text of this box must be hidden else it is 
irritating for the user.