How do I get out of an accidental huge paste in Calc

I am currently stuck waiting for Calc to paste over a million values because I accidentally highlighted the whole column instead of just one cell. This happens to me occasionally and is very frustrating.

Is there some way to abort it without losing other unsaved changes?

Is there some way I can have it ask me “Are you sure you want to do that?” when a huge number of cells are involved?

In Thunderbird, I sometimes miss highlighting a message, leaving the mailbox folder highlighted when deleting a message. It asks me, “Are you sure you want to delete that whole folder?” That has saved me a number of times. I need something like that in Calc.

I waited a little while, wrote and edited this entire message, and my processor fan is still going at full speed stressing my notebook! It’s going on 15 minutes with no end in sight (and I have a 5th gen i7 with 12GB ram).

I already typed a Ctrl+Z, but apparently Calc hasn’t bothered to notice it yet.

I never need huge spreadsheets. Mine almost never exceed a few hundred rows or 50 columns on one sheet. If I could work in fenced area that would be good too.

If it matters, I am using kubuntu 18.04 Linux and LO 1:6.0.7-0ubuntu0-18.04.10

When all else fails try the “Escape” key.