Just a few suggestions for the GUI.
Importing IP Addresses/Host Names:
+Add an option to APPEND the imported list to the IP Address Input Panel
+Add ability to alter the default options for the "Import IP/Host Names" process.
Barring that, having the program remember the previous options used would work for me. I rarely change which options I select, but I must change them every time.
On the first dialog, the selection under "Import these lines" > "Into the main view" or "Into the IP address input panel"
When importing Host names, the query about resolving them to IP addresses.
The "Rescan/Validate" dialog options.
Options > Program Options > Applications:
+Remember the previously set column widths, or even move this to a separate window and remember the column widths and window size.
+Remove ability to re-order by clicking on the column header. It's far too easy to miss the column width handle and accidentally reorder the applications. The only way to exit the window without setting the new application order is to click cancel (discarding all previous changes) and start over.
+Add the ability to select a block of Applications and move them as a unit.
+Add an easy way to sort by and remove dead hosts from the main view
During the scanning process:
+Handle requests to delete an item from the main view by adding them to a queue which will be executed when scanning concludes.
Filtering:
+Add conditions "Begins With" and "Ends With".
+Add support for "?" as a single-character wildcard.