Explain which menu bar items can be hidden

Hiding other apps' icons worked, but Apple pins Spotlight, Clock, Battery
and Control Center to the right of the menu bar, so a third-party item can
never be placed after them to push them away. Document the real limit so
the behaviour is not mistaken for a bug.

💘 Generated with Crush

Assisted-by: Crush:deepseek-v4.1-flash

README.md

@@ -27,11 +27,21 @@ still works.
 
 macOS has no public API to move another app's status item. The **Hide items from
 the menu bar** toggle uses the spacer technique: a zero-width status item is
-created at launch whose length is expanded to push the items to its left
-off-screen. This is reliable only when SimpleTopBar starts at login (its spacer
-then sits to the right of later-launched apps' items) and may need re-toggling
-after items move around. It is off by default and always undone on quit; if the
-app dies, macOS removes the spacer automatically.
+created at launch whose length is expanded to push the other icons off-screen so
+they only live in this panel. It is off by default and always undone on quit; if
+the app dies, macOS removes the spacer automatically.
+
+What it can and cannot hide:
+
+- It hides **other third-party apps' icons** (and can also catch some Apple
+  items such as Wi-Fi).
+- It **cannot** hide **Spotlight, Clock, Battery, or Control Center**. macOS
+  reserves the far right of the menu bar for those, and a third-party app cannot
+  place its item to their right, so there is nothing to push them with. (This is
+  the same limit Bartender and Ice hit; they cover the area with their own
+  overlay bar instead.)
+- Newly launched apps are placed to the left of the spacer, so they are hidden
+  automatically.
 
 ## Install with Homebrew