Please describe the problem:
Using the 'Other...' option in the dropdown above the folder list, navigation to folders with spaces in them doesn't work.

Steps to reproduce:
1. Start gthumb in folder view (as opposed to single-image view).
2. Click the folder dropdown and select "Other...".
3. Navigate to a directory with a name containing a space (for instance, "/home/user/pictures of ducks") and select Open in the file chooser.


Actual results:
While the user can navigate to this directory in the file chooser without issue, an error will be given when 'Open' is clicked: "Cannot load folder "file:///home/user/pictures%20of%20ducks": File not found". Navigating to a directory without spaces works as expected.

Expected results:
The selected directory should be opened.

Does this happen every time?
Yes, this is repeatable.

Other information:
A simple workaround is to navigate to the nearest directory without spaces in it, then navigate to the desired directory from there.

I'm using gthumb 2.7.6-0ubuntu1 on Ubuntu Dapper.