When working with an external JAR library, it is quite painful to have to type the name of the library class each time you load the library.
It would be great to have a Manifest attribute giving the name of the Library class.
That's what the attached patch does. It adds support for a "Library-Class" attribute in the Manifest. If found, Logisim uses it as the class name instead of displaying the dialog box. Otherwise, Logisim reverts to the good-old dialog box.