When created Class Viewer over a decade ago, really wanted configuration by XML file, and now that file is called ClassViewerConfig.xml where I didn't call it that at start. Changed to it recently, and I think is much better with that explanative name.
It is easily edited by text editor. So you can just open with a text editor and make changes.
Here is a bit from mine:
<Local> <BrowserLoc>C:\\Program Files\\Mozilla Firefox\\firefox.exe</BrowserLoc> <Editor>"C:\\Program Files\\gedit\\bin\\gedit.exe"</Editor> <acceptsLineNumber>Yes</acceptsLineNumber> <parameter>+</parameter> </Local>
That's from the top, where Class Viewer learns what browser you use. So can change to your own. And default is Firefox where I test. If another browser does not work well, sorry but am just supporting Firefox. That keeps it simple for me, and know is widely used enough should be ok for most.
Also a text editor for the use of Class Viewer can be specified. If it does not accept a line number parameter just change to: No
And Class Viewer can attempt to open a Java file to the method, if text editor does accept a line number parameter.