New workspaces grow in; config saves don't redraw everything or race; media peek skips the player in front

- A workspace Hyprland makes for a switch (createworkspacev2) grows into the row
  over the slide instead of appearing at full size; the window keeps the full
  room meanwhile.
- Every config.toml save restarted the colour Animation, and Animation::new
  runs its clock even from a colour to itself, so every window redrew for 0.4 s
  per save. The colours now only fade when they change.
- The file watch could read config.toml halfway through the shell's own save
  and reset settings to their defaults. Saves and rereads share one lock, the
  file is written to a new file and renamed over, and the shell's own saves
  are skipped by the watch.
- A song change or new player only pops the island when the focused window
  isn't that player's app (parse::same_app, tested).

src/theme.rs

@@ -76,24 +76,41 @@ impl Blend for Colors {
 
 pub struct Theme {
     colors: Animation<Colors>,
+    // where the colours are going; a reread that lands on them again starts no fade
+    target: Colors,
 }
 
 impl Service for Theme {
     fn new() -> Self {
-        Self { colors: Animation::new(fallback()) }
+        Self { colors: Animation::new(fallback()), target: fallback() }
     }
 
     /*
      * waits on the kernel instead of polling: amane::watch_file watches the folder, so
      * matugen writing a new file and renaming it over the old one is seen too.
-     * config.toml on its own thread, the theme here; either change re-reads both
+     * config.toml on its own thread, the theme here. a changed config.toml redraws
+     * everything; the colours fade only if it changed them (its fallback colours)
      */
     fn listen() {
-        reload();
+        reload(true);
 
-        thread::spawn(|| follow("config.toml"));
+        thread::spawn(|| {
+            for _ in amane::watch_file(&config_file("config.toml").to_string_lossy()) {
+                // one save can arrive as several writes: let it finish, then read once
+                thread::sleep(Duration::from_millis(50));
 
-        follow("theme");
+                if config::reread() {
+                    touch();
+                    reload(true);
+                }
+            }
+        });
+
+        for _ in amane::watch_file(&config_file("theme").to_string_lossy()) {
+            thread::sleep(Duration::from_millis(50));
+
+            reload(false);
+        }
     }
 }
 
@@ -102,41 +119,26 @@ pub fn touch() {
     let _ = Theme::write();
 }
 
-// what was read last, (theme, config.toml); none until the first read
-static LAST: Mutex<Option<(String, String)>> = Mutex::new(None);
+// the theme file as read last; none until the first read
+static LAST: Mutex<Option<String>> = Mutex::new(None);
 
-fn follow(name: &str) {
-    for _ in amane::watch_file(&config_file(name).to_string_lossy()) {
-        // one save can arrive as several writes: let it finish, then read once
-        thread::sleep(Duration::from_millis(50));
-
-        reload();
-    }
-}
-
-// a deleted theme file sends no event: the defaults come back at the next start
-fn reload() {
-    let read = (read("theme"), read("config.toml"));
+/*
+ * the theme file, read anew; `again` also when it's unchanged, for new fallback colours.
+ * a deleted theme file sends no event: the defaults come back at the next start
+ */
+fn reload(again: bool) {
+    let theme = fs::read_to_string(config_file("theme")).unwrap_or_default();
 
     let mut last = LAST.lock().unwrap_or_else(PoisonError::into_inner);
 
-    // a write that changes nothing redraws nothing
-    if last.as_ref() == Some(&read) {
+    if last.as_ref() == Some(&theme) && !again {
         return;
     }
 
-    if last.as_ref().is_none_or(|(_, config)| *config != read.1) {
-        config::apply_text(&read.1);
-    }
-
     // the colours at startup show at once, later changes cross-fade
-    apply(&read.0, last.is_none());
+    apply(&theme, last.is_none());
 
-    *last = Some(read);
-}
-
-fn read(name: &str) -> String {
-    fs::read_to_string(config_file(name)).unwrap_or_default()
+    *last = Some(theme);
 }
 
 // $XDG_CONFIG_HOME, or ~/.config
@@ -178,10 +180,16 @@ fn apply(theme: &str, startup: bool) {
         }
     }
 
+    if !startup && Theme::read().target == colors {
+        return;
+    }
+
     let fade = if startup { 0 } else { config::appearance::colors::transition_ms() };
 
     let mut theme = Theme::write();
 
+    theme.target = colors;
+
     // a change in the middle of a fade starts from the colours on screen now
     let now = theme.colors.value();