Not sure I quite understand your question. You do have the ability to resize partitions via disk utility. If you open disk utility and select the disk you want to resize you should see a few diagonal lines in the lower right corner. You simply drag from that point to resize the partition.
It doesn't work. I had 5 partitions. 3 with 250GB, 1 with 240GB and 1 with 10GB. I removed the last one, so now I have 4 partitions. Disk utility does not give me the 10GB back, no matter which partition I'm trying to resize.
So you are saying that when you resized the 240GB partition to include to 10GB space, that the partition did not show up as 250GB?
Correct.