What to do after mistakingly shrinking disk in Disk Utility?

I only had 1 volume on my hard drive. I tried to shrink it with Disk Utility - thinking it would resize the disk and the other space would be available to create another disk with. I didn't add any more partitions or try to format anything. I just slid the resize bar up and clicked apply. When it finished it said could not shrink disk. I haven't done anything from there but slide the size bar up and down.

Do I just restart the Mac or do I need to do something else to be sure that my hard drive is still its full size?