I noticed that with current pixman Git, the compiz window shadows are invisible. I bisected it to commit b24fc024fabed9406958611edc607f2af51e46cd ('Make fbFetchTransformed() used the new filtered many-pixel fetchers'), see the bisect log below.

This should be fixed before the 0.16 release, but I didn't see a blocker bug for that.

git bisect start
# bad: [d4dc812380f937908e466bfab52bfcc3b5334ebe] Get rid of pixman_region_internal_set_static_pointers()
git bisect bad d4dc812380f937908e466bfab52bfcc3b5334ebe
# bad: [2c70814b6bff2091bcc55ae4252fe82ae53439e4] Delete unused _pixman_image_get_fetcher() function
git bisect bad 2c70814b6bff2091bcc55ae4252fe82ae53439e4
# good: [6df6a43dc7119a510cf9db2e62fcc970a539e5a3] Bump version number pre release
git bisect good 6df6a43dc7119a510cf9db2e62fcc970a539e5a3
# good: [63c1ab031347dd2f26a25f29589516e1e59ba8db] Make pixman_implementation call the right combiner
git bisect good 63c1ab031347dd2f26a25f29589516e1e59ba8db
# bad: [dc0a9dd65ab2622646d1220adf3e5ea70dcae951] Remove all the srcRepeat/srcTransform stuff from the general implementation.
git bisect bad dc0a9dd65ab2622646d1220adf3e5ea70dcae951
# bad: [df23b360a0330e89c1f38f9d64e8ac150ea740e4] Remove unused code from pixman-transformed.c
git bisect bad df23b360a0330e89c1f38f9d64e8ac150ea740e4
# good: [da9f3266fd00a5634fd2fb8a9cffbf24d668aaab] In the mmx implementation, check for source == 0 rather than alpha == 0.
git bisect good da9f3266fd00a5634fd2fb8a9cffbf24d668aaab
# good: [d2cbfeca0efbf108c320e38bb39970af57c84438] Add _pixman_image_fetch_pixels()
git bisect good d2cbfeca0efbf108c320e38bb39970af57c84438
# bad: [e8b4ebf59143a04f5b6f10fb112d39ca50250293] Fix a couple of bugs in the bilinear fetcher
git bisect bad e8b4ebf59143a04f5b6f10fb112d39ca50250293
# good: [1510ffb750b8b74c32dffd11cc0f20ce091767c1] Add fetch_bilinear_pixels() function
git bisect good 1510ffb750b8b74c32dffd11cc0f20ce091767c1
# bad: [b24fc024fabed9406958611edc607f2af51e46cd] Make fbFetchTransformed() used the new filtered many-pixel fetchers
git bisect bad b24fc024fabed9406958611edc607f2af51e46cd
# good: [8e0ad050e7ce7b3200e6126f782bad94d9df97f6] Add fetch_convolution_pixels() function
git bisect good 8e0ad050e7ce7b3200e6126f782bad94d9df97f6