I'm sorry I've been slow to respond. As a user of one of our commercial products you are eligible for e-mail support, which receives more immediate attention.
I've had a look FTPConnectionEditor and PropertyGrid which it extends. I haven't found any way to disable text-editing while still allowing the button to work. If you like you can have the source-code for FTPConnectionEditor and try to get it to work the way you want yourself.
- Hans (EnterpriseDT)