Here's a testcase (.tar.gz containing Makefile and testcase.c) using only Gtk, Gdk, and cairo, that shows the same problem with the Intel X driver. It should draw a deep red equilateral triangle, but nothing shows up with the Intel driver.
(I tried to write an equivalent Xlib testcase using XFillPolygon, but it didn't show the bug; so I clearly don't know enough about cairo to reduce this to an Xlib testcase.)
Here's a testcase (.tar.gz containing Makefile and testcase.c) using only Gtk, Gdk, and cairo, that shows the same problem with the Intel X driver. It should draw a deep red equilateral triangle, but nothing shows up with the Intel driver.
(I tried to write an equivalent Xlib testcase using XFillPolygon, but it didn't show the bug; so I clearly don't know enough about cairo to reduce this to an Xlib testcase.)