Please describe the problem:
If a drive cannot be unmounted from the drive mounter applet, two dialog boxes are  displayed.  The first dialog box (presented by gnome-mount) states that "An application is preventing..." and correctly presents the unmounting error.  Immediately afterward, a second dialog (part of the drivemount applet) appears with no text in it.  This second dialog is unnecessary and confusing.

Steps to reproduce:
1. Mount a drive with the Gnome mount applet.
2. Open a terminal and "cd" into the mountpoint for the drive.
3. Attempt to unmount the drive from the Gnome mount applet.



Actual results:
A second, useless, error dialog appears.

Expected results:
Only one dialog (probably from gnome-mount) should appear.

Does this happen every time?
Yes, confirmed on multiple systems.

Other information:
Originally reported in Ubuntu: https://bugs.launchpad.net/ubuntu/+source/gnome-applets/+bug/118467

A little more information: it seems that mount_result in drive-button.c of gnome-applets produces its own error dialog in addition to that produced by gnome-umount in gnome-mount. Is this dialog necessary at all? It seems that char *error is empty anyway.

This should be a relatively simple fix, I'm just not sure of the exact codepaths leading to mount_result.