Regarding Rapidweaver 6.3.4 on El Capitan
Suddenly the Pages menu, which is normally on the left side of the screen, disappeared!
I can’t find any setting which allows to turn it on/off and currently I am not able to navigate between the different pages of the project.
There were source list issues fixed back in 6.0.4 so this sounds odd, but this can hang over from the previous version, or you can show/hide it using the Show Source List in the View menu - so check that first.
If using the options in the View menu doesn’t help, then try this.
Quit RapidWeaver
Open the Terminal.app (found in Utilities in Applications) and enter the following command:
defaults delete com.realmacsoftware.rapidweaver6 “NSSplitView Subview Frames Main Document SplitView”