Resize root filesystem in gparted

Question

I'm trying to reisize my root filesystem in gparted, but when I try to drag the partition it won't do anything. if I change the number in the size field, it jumps back to where it was before. I need to resize it in order to make space for dual-booting Windows 10. This is my internal hard drive, /dev/sda:

partition map

Green is /dev/sda1, mounted at /boot/efi,
Blue is /dev/sda2, mounted at /,
Red is /dev/sda3, a linux swap, and
Grey is free space, there's only 1.02 MiB, obviously not enough for Windows 10, or really anything.

I select /dev/sda2 and click Partition > Resize/Move. I can't drag the partition or change the size number. This is what it looks like.

resize/move menu

I sincerely hope that someone will help. thanks

Update:

I found what might be a clue. There is a little icon of a key beside the name in the partition list. does that mean the partition is "locked" at its size? If so, how can I "unlock" it?

Answer 1

You may have to unmount the partitions.

Refer to the following question for more information: https://askubuntu.com/questions/277399/how-to-unlock-partition-in-gparted

If partitions are showed with a lock in gparted, then they are mounted. Usually gparted is able to unmount them, but sometimes this isn't possible, so you have to manually unmount them...