Jacek Caban (@jacek) commented about dlls/mshtml/mshtml_private.h:
struct list sibling_entry; struct wine_rb_entry entry;
- struct list detached_inner_windows;
Instead of special-casing detached windows, I think it would be cleaner to have a list of all inner windows (including the one that's currently active). To check if a window is detached, you may simply compare the current active window pointer to the one you're testing.