apologies for taking my sweet time in responding.
so what I am trying to do is set the modeline to be a bit different depending on which window is currently selected. as it stands, there is a `mode-line` face and a `mode-line-inactive face`. somehow emacs changes the default face for each mode-line depending on whether it is for the "active" window or not. I want to be able to customize other parts of the mode-line depending on whether it is selected or not.
for example, you cannot make the `mode-line-buffer-id` face different depending on whether its being displayed in the active window or not.
so the code I had written was able to detect whether the mode-line was being displayed in the active window or not.
now that things have changed, my code falls on its face. the currently suggested method is to wrap advice around the "select-window" function and add a few hooks.