uring != dead_caron+u, Compose

[Jan Martinek <honza dp fyz fce vutbr cz>]

Hello,

I used to type "uring" (letter u with ring above, Å,Å) by pressing
dead_caron and then letter u (or U). It works for me in many
applications like rxvt, xterm, qt-based and others, but it does not
work in Gtk2 applications. Computer only beeps but types nothing.
So to the file /usr/X11R6/lib/X11/locale/en_US.UTF-8/Compose
I added the following lines:

<dead_caron> <u>        : "Å" U016F # LATIN SMALL LETTER U WITH RING ABOVE
<Multi_key> <c> <u>     : "Å" U016F # LATIN SMALL LETTER U WITH RING ABOVE

but small letter u with ring above cannot be typed this way in gtk2.
This information may be irrelevant, but just for sure:
In the file
/usr/X11R6/lib/X11/locale/iso8859-2/Compose
there is a line

<dead_caron> <u>                        : "\371"        uring

Before starting an application for testing, I set the environment
this way:

export LC_ALL="en_US.UTF-8"

and keyboard layout is

setxkbmap cz

What can I do for typing [uU]ring by using dead_caron?

Thank you,
Jan Martinek