xemacs: bizarre buffer/window behaviours, scrollbars flicker

Binary package hint: xemacs21

Environment: Ubuntu 6.06.1, XEmacs 21.4.18 (= version 21.4.18-1ubuntu1 of package xemacs21-gnome-mule, still current as of 2007-05-31; "This version has also been compiled to use features from gtk and gnome.")

I encounter two strange (and possibly related) phenomena I have never seen been before in any Emacs:

1) Bizarre behaviour in buffer or window selection

When the frame is split vertically in two windows, the functions delete-other-window and delete-window sometimes delete the wrong window. In some cases, they even delete both windows and leave the frame with a single window showing a completely different buffer.

While switch-to-buffer seems to select the wrong buffer only rarely, this happens frequently when selecting a buffer to display using electric-buffer-list. This function may take up to 10 sec before displaying the buffer "Electric Buffer List" holding the list of available buffers. Sometimes this buffer is not shown at all, but instead some other buffer.

I have the impression that issuing these commands more slowly (i.e. pressing the function keys to which they are bound more carefully) helps to reduce the frequence of problem, but this might be pure illusion.

Bug #3184 mentions a similar observation on the side, but the main bug described there (XEmacs showing the scratch buffer when run with a file argument) does not occur for me, so I opened this new bug report. Bug #50396 seems to be a dup of Bug #3184.

2) Flickering scrollbars and gutter tabs area not redrawn

Most of the time, the gutter tabs area is not properly redrawn automatically, leaving stripes and such (but calling function recenter with Ctrl-L will cause it to be redrawn).

Under circumstances quite impossible to reproduce, the scrollbars are constantly flickering by an interval of a few seconds, without any user interaction with XEmacs. It seems that this occurs more often when the XEmacs frame does not have the focus, and when there are several (about 3, 4 or 5) XEmacs frames open.

I suspect that both problems are related to interaction with Gnome/GTK or with Metacity (it seems that it sometimes uses much more of the CPU when XEmacs has flickering scrollbars).