I love the function where you can choose between filling a column with the same value or with sequential values. The way you can choose between the two (by pressing shift as you enter your value)  is not very discoverable though.  I had to look it up in the manual even though I knew the function existed and the plus sign was there in front of me!

There are a few ways to improve this:

- make a hover-over hint when you move your mouse over the plus or equal signs.

- make the plus or equal signs clickable to woggle between the two

- let the plus or equal keys toggle between the two

or any other way to make the function more discoverable or easier to memorize.