I wanted to have Ubuntu with full disk encryption on one big partition, and Windows on a small one. In 12.04, only the Server Edition installer has full disk encryption, so I used that and then installed ubuntu-desktop. When it asked for the size, I reduced it from ~999GB to ~750gb. Now after the install, on both
disk utility I see /dev/sda2 taking ~931GB, and nothing unallocated, so I can't create a partition for windows.
I got the size right, because when I right-click inside a folder, then hit 'properties', I see
Free space: ~690GB (I don't know why it's not ~750GB, but at least it's not >900). The command
df -h shows the same.
So what can I do? Normally I would just resize a partition with gparted to create unallocated space, then create the partition. But here I have two problems: gparted does not seem to be showing the correct values, and also it says it does not support LUKS so I'm afraid it will mess things up.