While a build is in the queued state, I can cancel it from the project page, but I cannot cancel it from the 'all builds' page. That's a bit maddening: the 'latest builds' section should be identical in both pages.
http://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/?id=3c5e2917604315775eebe7e62a560a853e5b1c58
Verified on fido: 51246bfae3b0012a5940ce744816de70ccbf1292