we are using Synchronize It! to sync our production environment with our development environment. To find the files that need to be synced for a particular task, we create a list of all files inside this task and add it to the field "Files:" in the settings-dialog. When pasting the values into the field, they are not displayed correctly and when clicking "Preview", the application crashes.
You can find the string, we are pasting in there, here: http://pastebin.com/B0yx26qW
I admit, that it is a bit long for this field. But shorter strings are working fine and I hope that you do not see a general issue in allowing longer strings as well
Happens in both: 3.4 and 3.5