Allow to cancel mport and refresh

What steps will reproduce the problem?
1. start to import or refresh a folder
2. change your mind or discover you chose the wrong folder
3. try to cancel the operation

What is the expected output? What do you see instead?
I'd like to have a Cancel button to allow me to stop.

What version of the product are you using? On what operating system?
jBrout 0.3.145 r168 / XP SP3

Please provide any additional information below.
This is low priority, but this has happened often to me: I ask for a full
refresh (15 minutes), then jBrout crashes the refresh on one of the last
pictures (Murphy's law). So I remove the faulty picture from the folder
(with another tool, of course), then I right-click on the folder and I
select Refresh. Usually, in Windows, when you right-click somewhere, that
"somewhere" becomes automatically selected. Not in jBrout, but this may be
a problem with Python, and anyhow this would be a separate issue. I forget
that jBrout will apply the refresh to the root folder because the root
folder is still selected. So I trigger a full refresh (15 minutes again)
while all I wanted was refreshing a few dozen pictures :-(

Original issue reported on code.google.com by davito...@gmail.com on 21 Jan 2009 at 8:19

brunolojor / jbrout

Allow to cancel mport and refresh #44