I've just accidentally dragged a file ontop of an archive
(whilst trying to drag a box around the two items). The
resulting "adding item to archive" popup has a progress bar
and a cancel button on it. The cancel button doesn't
achieve anything obvious in the UI, at least.

Eventually (20 seconds or so later) the popup disappears
and I get a dialogue which reads

    An error occured while adding files to
    the archive.

    (null)

                            OK

package file-roller
retitle 525106 file-roller: doesn't respond to cancel request from Nautilus
found 525106 2.28.2-1
thanks

I tested this using version 2.28.2-1 of ‘file-roller’, version
2.28.4-1 of ‘nautilus’.

I don't get the reported error message. However, the main reported
behaviour (the cancel button has no effect) I managed to reproduce
following these steps:

=====
Script started on Sun 28 Feb 2010 18:45:06 EST
$ workdir=$(mktemp -t -d)

$ tarfile=${workdir}/test.tar
$ tar -cf ${tarfile} /dev/null
tar: Removing leading `/' from member names

$ dd if=/dev/zero count=1024 bs=1024K of=${workdir}/foo
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 18.667 s, 57.5 MB/s

$ nautilus ${workdir}
[… Within the resulting Nautilus window:

* Drag the entry ‘foo’ onto the entry ‘test.tar’.

  * A dialogue box appears titled “Adding files to archive”, with a
    progress bar.

  * The progress bar jumps to 50% and stays there.

* While the dialogue box remains, select the “Cancel” button.

  * The button has no apparent effect.

  * Eventually, the dialogue box disappears.

* Close the Nautilus window.
…]

$ ls ${tarfile}
/tmp/tmp.yQtpbG0iqH/test.tar

$ tar -tvf ${tarfile}
crw-rw-rw- root/root       1,3 2009-12-24 09:10 dev/null
-rw-rw-r-- bignose/bignose 1073741824 2010-02-28 18:51 foo

$ rm -rf ${workdir}

$ exit

Script done on Sun 28 Feb 2010 18:53:37 EST
=====

Instead, selecting “Cancel” in Nautilus's “Adding files to archive”
dialogue box should cancel the operation, leaving the archive in its
original state.