I think in your rush to be sarcastic you forgot to read the part where I gave "application logic" and "library logic" some practical definitions :)
To clarify anyway - "tiling vs free-floating" is an application behaviour, "move window from (x1,y1) to (x2,y2)" is a library function; "focus follows mouse vs click-to-focus" is an application behaviour, "set_focus(window_id)" is a library function; "apps have icons vs apps have text labels" is an application behaviour, "render_icon()" and "render_text()" are library functions; etc.
As somebody who is interested in creating my own window manager, because none of the existing ones behave in the way that I want them to, I find the definition used by the author here to be very useful - the 500 lines are what I need to grok in order to build a WM which works in the way I want it to, and the 40,000 lines are what I can just call without needing to care about the internals. (To use parent's 2-line example as a counterexample - grokking those two lines is not sufficient to build the WM of my dreams)
To clarify anyway - "tiling vs free-floating" is an application behaviour, "move window from (x1,y1) to (x2,y2)" is a library function; "focus follows mouse vs click-to-focus" is an application behaviour, "set_focus(window_id)" is a library function; "apps have icons vs apps have text labels" is an application behaviour, "render_icon()" and "render_text()" are library functions; etc.
As somebody who is interested in creating my own window manager, because none of the existing ones behave in the way that I want them to, I find the definition used by the author here to be very useful - the 500 lines are what I need to grok in order to build a WM which works in the way I want it to, and the 40,000 lines are what I can just call without needing to care about the internals. (To use parent's 2-line example as a counterexample - grokking those two lines is not sufficient to build the WM of my dreams)