Minecraft 1.8 - Making the fill and clone commands easier to use

To my knowledge there are no mods like this at all, and if there were any they would not be up to date with the 1.8 prereleases/snapshots. However there are a couple of tips to making easier use of the commands:

1. Hitting Tab will automatically fill out the coordinates of the block you are looking at.

   

   This is a much faster way of filling out coordinates than typing it in manually from the F3 screen. Hitting Space then Tab three times will correctly enter the X, Y and Z of the block your cross-hair is over.

2. Enter can be used to submit and "save" a half-completed command, then press Up while in chat to bring it back up and complete it.

   

   As the command does not have the correct syntax, you will get an error message when pressing Enter and nothing will happen, but you can still use Up to get the command that you entered back.

   Using this in combination with the previous trick allows you to move and easily enter both sets of coordinates into the command, without writing or even copy pasting anything.