The reason double-clicking got worse from 3.6.3 to now is this.  Previously, browser.ModuleBrowserTreeItem.OnDoubleClick ignored the file_open global (set to pyshell.flist.open in .__init__) and called pyshell.flist.open.  The Class and Method OnDoubleClick called file_open.  So double-clicking a file name in pathbrowser opened the file, but expanding a file and double-clicking a class or function name raised "'NoneType' object is not callable".  I don't know if I ever tried the latter before.  We subsequently changed the Module DoubleClick to also use file_open, so double clicking a file name also raises. (I meant to submit this yesterday.)