the attached patch fixes the bug for me...
(taken from:
http://lists.gnu.org/archive/html/qemu-devel/2008-11/msg00116.html )
--- kvm-72+dfsg/qemu/keymaps/modifiers 2008-07-27 12:08:56.000000000 +0200
+++ kvm-72+dfsg.new/qemu/keymaps/modifiers 2008-11-14 11:45:42.000000000 +0100
@@ -3,6 +3,7 @@
Alt_R 0xb8
Mode_switch 0xb8
+ISO_Level3_Shift 0xb8
Alt_L 0x38
Control_R 0x9d
--- kvm-72+dfsg/qemu/vnc_keysym.h 2008-07-27 12:08:56.000000000 +0200
+++ kvm-72+dfsg.new/qemu/vnc_keysym.h 2008-11-14 11:47:16.000000000 +0100
@@ -204,6 +204,7 @@
{"EuroSign", 0x20ac}, /* XK_EuroSign */
/* modifiers */
+{"ISO_Level3_Shift", 0xfe03}, /* XK_ISO_Level3_Shift */
{"Control_L", 0xffe3}, /* XK_Control_L */
{"Control_R", 0xffe4}, /* XK_Control_R */
{"Alt_L", 0xffe9}, /* XK_Alt_L */
@@ -286,6 +287,28 @@
{"Pause", 0xff13}, /* XK_Pause */
{"Escape", 0xff1b}, /* XK_Escape */
+/* dead keys */
+{"dead_grave", 0xfe50}, /* XK_dead_grave */
+{"dead_acute", 0xfe51}, /* XK_dead_acute */
+{"dead_circumflex", 0xfe52}, /* XK_dead_circumflex */
+{"dead_tilde", 0xfe53}, /* XK_dead_tilde */
+{"dead_macron", 0xfe54}, /* XK_dead_macron */
+{"dead_breve", 0xfe55}, /* XK_dead_breve */
+{"dead_abovedot", 0xfe56}, /* XK_dead_abovedot */
+{"dead_diaeresis", 0xfe57}, /* XK_dead_diaeresis */
+{"dead_abovering", 0xfe58}, /* XK_dead_abovering */
+{"dead_doubleacute", 0xfe59}, /* XK_dead_doubleacute */
+{"dead_caron", 0xfe5a}, /* XK_dead_caron */
+{"dead_cedilla", 0xfe5b}, /* XK_dead_cedilla */
+{"dead_ogonek", 0xfe5c}, /* XK_dead_ogonek */
+{"dead_iota", 0xfe5d}, /* XK_dead_iota */
+{"dead_voiced_sound", 0xfe5e}, /* XK_dead_voiced_sound */
+{"dead_semivoiced_sound", 0xfe5f}, /* XK_dead_semivoiced_sound */
+{"dead_belowdot", 0xfe60}, /* XK_dead_belowdot */
+{"dead_hook", 0xfe61}, /* XK_dead_hook */
+{"dead_horn", 0xfe62}, /* XK_dead_horn */
+
+
/* localized keys */
{"BackApostrophe", 0xff21},
{"Muhenkan", 0xff22},
