Description of Problem:

When you open an URI in Nautilus, and the URI is
unreachable or takes time to be reached, Nautilus
displays a dialog asking users whether they want
to cancel the opening.

The current dialog looks like that:

Window Title: Cancel Open?
Text:         Opening "Filesystem"
Button:       Cancel

This dialog is confusing because you don't know
what Nautilus is doing, and what the "cancel"
button will actually do.

Here is a proporisition to replace it:

+--------------------------+
|                          |
| Opening {URI}            |
| |---[////]-------------] |
|                          |
|                [Cancel]  |
+--------------------------+

The [////] symbol is an indeterminateprogress
indicator [1]

[1]
http://developer.gnome.org/projects/gup/hig/1.0/feedback.html#indeterminate-progress