make indicator Cancel button a bit more prominent

[kevinushey]

Verified in 2023.09.0-daily+290 on MacOS 13.5. However, the Cancel option is almost indistinguishable from the rest, so I overlooked it the first couple of times that I tried it—I kept trying the big grayed-out button below. Is there any way to distinguish it a little more, such as by putting a border around it so that it looks like a button?

Originally posted by @ronblum in #13312 (comment)

[ronblum]

Thanks @kevinushey! I guess I got a little lazy and didn't open a new issue for this. I'll go close the other one.

[kevinushey]

This issue should now be obviated: rather than include a Cancel button in the progress label, we allow the user to click the "regular" Cancel button in the dialog.

[jonvanausdeln]

Verified with 2023.12.0-daily+268
Windows 11, MacOS 12.6

Cancel Button on Dialog works as expected now and is visible.