Comment 3 for bug 1164787

I just found that this bug also exists in 12.04 64 bits.

it's not the sort of thing you are likely to notice unless you are looking for it.

my disk has 14 partitons on it that may be a factor.

I now know what the difference is between when it works and when it does not work.

When you first enter this screen, the slider is missing the final partition.

However, after you make a change, e.g. choose an existing partition to install to, then the missing slider bar entry magically appears.

So the initial value is wrong, but the recomputed value is correct.