I have build gnumeric using the experimental Mac OS X Quartz gtk backend.  I am using:

gnumeric 1.7.7 (SVN)
gtk as of 13 Jan 07
cairo as of 13 Jan 07

To reproduce:
1.  Execute gnumeric.
2.  Click on the "File" menu.  Drag the mouse down to "Open."  As soon as Open
is highlighted by the mouse, gnumeric will crash with:

cairo.c:88: failed assertion `status > CAIRO_STATUS_SUCCESS && status <=
CAIRO_STATUS_LAST_STATUS'


Stack trace:
Program received signal SIGABRT, Aborted.
0x9003d1dc in kill ()
(gdb) ba
#0  0x9003d1dc in kill ()
#1  0x9010f2af in raise ()
#2  0x9010de02 in abort ()
#3  0x02e7c5b0 in __eprintf ()
#4  0x02e27ecf in _cairo_error (status=1001) at cairo.c:87
#5  0x02e3920f in cairo_scaled_font_glyph_extents (scaled_font=0x36efd20,
glyphs=0xbfffd1dc, num_glyphs=1, extents=0xbfffd180) at cairo-scaled-font.c:722
#6  0x000c6f35 in pango_cairo_atsui_font_get_glyph_extents (font=0x35fe0f0,
glyph=65535, ink_rect=0x0, logical_rect=0xbfffd230) at
pangocairo-atsuifont.c:182
#7  0x03776bbd in set_glyph (font=0x0, glyphs=0xef2b4c0, i=-1073754084,
offset=8, glyph=65535) at basic-atsui.c:94
#8  0x03776df5 in basic_engine_shape (engine=0x35fd390, font=0x35fe0f0,
text=0xf0368a0 "Open a file", length=11, analysis=0xef28704, glyphs=0xef2b4c0)
at basic-atsui.c:167
#9  0x02da16a9 in pango_shape (text=0xf0368a0 "Open a file", length=11,
analysis=0xef28704, glyphs=0xef2b4c0) at shape.c:51
#10 0x02d94729 in shape_run (line=0xef2fe10, state=0xbfffd550, item=0xef286f8)
at pango-layout.c:2896
#11 0x02d97733 in process_item (layout=0xef2d618, line=0xef2fe10,
state=0xbfffd550, force_fit=1, no_break_at_end=0) at pango-layout.c:2988
#12 0x02d97c40 in pango_layout_check_lines (layout=0xef2d618) at
pango-layout.c:3223
#13 0x02d9859d in pango_layout_get_extents_internal (layout=0xef2d618,
ink_rect=0x0, logical_rect=0xbfffd6f8, line_extents=0x0) at pango-layout.c:2198
#14 0x02d9956e in pango_layout_get_pixel_extents (layout=0xef2d618,
ink_rect=0x0, logical_rect=0xbfffd6f8) at pango-layout.c:2400
#15 0x02061f8c in gtk_progress_bar_size_request (widget=0x35e68a8,
requisition=0x35e68c4) at gtkprogressbar.c:518
#16 0x0330604e in g_closure_invoke (closure=0x367a120, return_value=0x0,
n_param_values=2, param_values=0xbfffd990, invocation_hint=0xbfffd898) at
gclosure.c:490
#17 0x033160ab in signal_emit_unlocked_R (node=0x367a170, detail=0,
instance=0x35e68a8, emission_return=0x0, instance_and_params=0xbfffd990) at
gsignal.c:2370
#18 0x03317ef9 in g_signal_emit_valist (instance=0x35e68a8, signal_id=28,
detail=0, var_args=0xbfffdbcc "?\"\t\002?h^\003?\002") at gsignal.c:2199
#19 0x0331b3b8 in g_signal_emit_by_name (instance=0x35e68a8,
detailed_signal=0x219f1b0 "size_request") at gsignal.c:2267
#20 0x020930f5 in do_size_request (widget=0x35e68a8) at gtksizegroup.c:592
#21 0x020934ab in _gtk_size_group_compute_requisition (widget=0x35e68a8,
requisition=0xbfffdc38) at gtksizegroup.c:792
#22 0x01fe3bb3 in gtk_hbox_size_request (widget=0xece82c0,
requisition=0xece82dc) at gtkhbox.c:97
#23 0x0330604e in g_closure_invoke (closure=0x367a120, return_value=0x0,
n_param_values=2, param_values=0xbfffdeb0, invocation_hint=0xbfffddb8) at
gclosure.c:490
#24 0x033160ab in signal_emit_unlocked_R (node=0x367a170, detail=0,
instance=0xece82c0, emission_return=0x0, instance_and_params=0xbfffdeb0) at
gsignal.c:2370
#25 0x03317ef9 in g_signal_emit_valist (instance=0xece82c0, signal_id=28,
detail=0, var_args=0xbfffe0ec "?\"\t\002Ȃ?\016?\002") at gsignal.c:2199
#26 0x0331b3b8 in g_signal_emit_by_name (instance=0xe
ce82c0,
detailed_signal=0x219f1b0 "size_request") at gsignal.c:2267
#27 0x020930f5 in do_size_request (widget=0xece82c0) at gtksizegroup.c:592
#28 0x020934ab in _gtk_size_group_compute_requisition (widget=0xece82c0,
requisition=0xbfffe158) at gtksizegroup.c:792
#29 0x021420b9 in gtk_vbox_size_request (widget=0x2370b8, requisition=0x2370d4)
at gtkvbox.c:95
#30 0x0330604e in g_closure_invoke (closure=0x367a120, return_value=0x0,
n_param_values=2, param_values=0xbfffe3d0, invocation_hint=0xbfffe2d8) at
gclosure.c:490
#31 0x033160ab in signal_emit_unlocked_R (node=0x367a170, detail=0,
instance=0x2370b8, emission_return=0x0, instance_and_params=0xbfffe3d0) at
gsignal.c:2370
#32 0x03317ef9 in g_signal_emit_valist (instance=0x2370b8, signal_id=28,
detail=0, var_args=0xbfffe60c "?\"\t\002?p#") at gsignal.c:2199
#33 0x0331b3b8 in g_signal_emit_by_name (instance=0x2370b8,
detailed_signal=0x219f1b0 "size_request") at gsignal.c:2267
#34 0x020930f5 in do_size_request (widget=0x2370b8) at gtksizegroup.c:592
#35 0x020934ab in _gtk_size_group_compute_requisition (widget=0x2370b8,
requisition=0xbfffe678) at gtksizegroup.c:792
#36 0x02159cdd in gtk_window_size_request (widget=0x35ca208,
requisition=0x35ca224) at gtkwindow.c:4443
#37 0x0330604e in g_closure_invoke (closure=0x367a120, return_value=0x0,
n_param_values=2, param_values=0xbfffe8f0, invocation_hint=0xbfffe7f8) at
gclosure.c:490
#38 0x033160ab in signal_emit_unlocked_R (node=0x367a170, detail=0,
instance=0x35ca208, emission_return=0x0, instance_and_params=0xbfffe8f0) at
gsignal.c:2370
#39 0x03317ef9 in g_signal_emit_valist (instance=0x35ca208, signal_id=28,
detail=0, var_args=0xbfffeb2c "?\"\t\002\020?\\\003?\002") at gsignal.c:2199
#40 0x0331b3b8 in g_signal_emit_by_name (instance=0x35ca208,
detailed_signal=0x219f1b0 "size_request") at gsignal.c:2267
#41 0x020930f5 in do_size_request (widget=0x35ca208) at gtksizegroup.c:592
#42 0x020934ab in _gtk_size_group_compute_requisition (widget=0x35ca208,
requisition=0x0) at gtksizegroup.c:792
#43 0x0215b160 in gtk_window_compute_configure_request (window=0x35ca208,
request=0xbfffed7c, geometry=0xbfffed38, flags=0xbfffed8c) at gtkwindow.c:5296
#44 0x0215bbe4 in gtk_window_check_resize (container=0x35ca208) at
gtkwindow.c:5508
#45 0x0330604e in g_closure_invoke (closure=0x367cc80, return_value=0x0,
n_param_values=1, param_values=0xbffff000, invocation_hint=0xbfffef08) at
gclosure.c:490
#46 0x033165eb in signal_emit_unlocked_R (node=0x367c620, detail=0,
instance=0x35ca208, emission_return=0x0, instance_and_params=0xbffff000) at
gsignal.c:2478
#47 0x03317ef9 in g_signal_emit_valist (instance=0x35ca208, signal_id=89,
detail=0, var_args=0xbffff21c
"???\001???\001\b?\\\003H???0??\001\b?\\\003\020?c\003H????}>\003?5?\002?\v")
at gsignal.c:2199
#48 0x033182f0 in g_signal_emit (instance=0x35ca208, signal_id=89, detail=0) at
gsignal.c:2243
#49 0x01f8c5a7 in gtk_container_check_resize (container=0x35ca208) at
gtkcontainer.c:1182
#50 0x01f8c630 in gtk_container_idle_sizer (data=0x0) at gtkcontainer.c:1108
#51 0x02ae3618 in gdk_threads_dispatch (data=0xef2b7d0) at gdk.c:470
#52 0x033e8aeb in g_main_context_dispatch (context=0x361ae00) at gmain.c:2049
#53 0x033ebe3f in g_main_context_iterate (context=0x361ae00, block=1,
dispatch=1, self=0x3607010) at gmain.c:2681
#54 0x033ec1dd in g_main_loop_run (loop=0x36faf30) at gmain.c:2885
#55 0x02022346 in gtk_main () at gtkmain.c:1135
#56 0x00003fe3 in main (argc=1, argv=0xbffff560) at main-application.c:533

Other information:
I am using Mac OS X 10.4.8.