No gutter visible under AIX / X11

I've tested the gutter on XEmacs under NT (21.2-b19, which I got from ftp.ese-metz.fr/pub/xemacs/win32) and think it's really cool, so I wanted to have it also on the XEmacs running on my AIX (4.3.2) box (also 21.2-b19, which I built myself from the tarballs). Unfortunately *no* gutter at all is visible, although the "Visible" button under "Options->Gutter Apperarance" is on. (In addition to that, I don't see the function `buffers-tab-selection-function' on AIX, but it exists on NT.) Is this a known problem? Or no problem at all and I'm doing something wrong? (e.g. do I have to specify additional parameters with configure or something similar?) TIA for any hint! Markus --- Markus Alt IBM Laboratory Boeblingen, Germany