Forgive me if you are already planning the following improvement but since it is badly needed I will suggest it anyway.
I think a very necessary improvement would be the incorperation of progress bars to all of the available program functions. Import/Export etc. I notice you have one progress bar for the "Check Links" function. However even though I haven't explored every option, and function, it would appear most functions do not have progress bars. Some method of informing the user that the program has not crashed or in a infinite loop is one of the most important features of all software.
They should be fairly easy to implement.