inspect.signature is now the official way to get signatures (sort of the 3rd). It now works with some builtins, and will work with most by the time 3.5 is released. It includes removing the first parameter of bound methods. If it does not work correctly for some case (as 'correctly' is generally agreed on), an issue should filed to fix it.

#19903 is about changing calltips, but only for 3.4+. The tests will have to be changed and can perhaps be reduced. I have not done it yet because .signature was still being worked on until a few weeks ago.

From my reading of pyclbr, I expected it to detect nested classes. I saw specific code to ignore nested functions, as they are generally not accessible from outside the outer function, whereas nested classes are as accessible as methods. But a simple test with
class C:
    class inner:
        def innerf(): pass
    def Cfunc(): pass
shows that I was wrong. Class inner is not listed, but it should be. I think it would be simple to treat it as if it were a method, but use a Class instance. If you want to work on this, open a new issue.

There are three other problems I encountered while testing.

1. If I edit the file and open CB, it ignores an existing (obsolete) CB window and open a new one instead of reusing the existing window or closing it first. Sometimes it opens the new one exactly on top of the old one.

2. If I forget to save, it uses the obsolete data on disk. This is why I like the idea of using the live text. Barring that, I think there should be an message box offering to save and open the window or cancel.

Fixing either of these would involve the code that responds to Alt-C or the menu entry, which is somewhere other than ClassBrowser.py. Again, these would be new issues.

3. On my screen, each line cuts off the bottom of the line above. This might be due to the icons being 'too big' (but I think they are a standard 16x16). Or perhaps me using Windows' 125% text size setting. I have no idea whether this can be fixed in Idle's use of the Tree widget or is ultimately a bug in the Tk code.

These all bother me more than having to double click a function name to get its signature.