diff --git a/Cargo.lock b/Cargo.lock
index b124450..adf8c7f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4,9 +4,12 @@ version = 3
 
 [[package]]
 name = "accesskit"
-version = "0.22.0"
+version = "0.23.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3eca13c82f9a5cd813120b2e9b6a5d10532c6e4cd140c295cebd1f770095c8a5"
+checksum = "0467c58e646d849edd7fe043d6711b8ad58f27a39a5f33886f1f2ca9852e8259"
+dependencies = [
+ "uuid",
+]
 
 [[package]]
 name = "accesskit-c"
@@ -20,9 +23,9 @@ dependencies = [
 
 [[package]]
 name = "accesskit_atspi_common"
-version = "0.15.0"
+version = "0.16.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3eb9cc46b7fb6987c4f891f0301b230b29d9e69b4854f060a0cf41fbc407ab77"
+checksum = "c6778622dca77b55464f993289ffa9c2f192976e5891c2c30e2439af61b6ddf2"
 dependencies = [
  "accesskit",
  "accesskit_consumer",
@@ -33,9 +36,9 @@ dependencies = [
 
 [[package]]
 name = "accesskit_consumer"
-version = "0.32.0"
+version = "0.33.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "69d880a613f29621c90e801feec40f5dd61d837d7e20bf9b67676d45e7364a36"
+checksum = "6fce4cd9f6ea13c76d53403ff1583163f7a9e58381ecfbf4c8449affd7c09c24"
 dependencies = [
  "accesskit",
  "hashbrown",
@@ -43,9 +46,9 @@ dependencies = [
 
 [[package]]
 name = "accesskit_macos"
-version = "0.23.0"
+version = "0.24.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5b0ddfc3fe3d457d11cc1c4989105986a03583a1d54d0c25053118944b62e100"
+checksum = "c001a603b958865ce466c92ac2487041ff402f994c705a3f12a5765e4e54a35e"
 dependencies = [
  "accesskit",
  "accesskit_consumer",
@@ -57,9 +60,9 @@ dependencies = [
 
 [[package]]
 name = "accesskit_unix"
-version = "0.18.0"
+version = "0.19.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d5d552169ef018149966ed139bb0311c6947b3343e9140d1b9f88d69da9528fd"
+checksum = "f861c80792fd2f3d0fccd89be70ecd76295b9ea641e6116e331036cec0cec707"
 dependencies = [
  "accesskit",
  "accesskit_atspi_common",
@@ -75,9 +78,9 @@ dependencies = [
 
 [[package]]
 name = "accesskit_windows"
-version = "0.30.0"
+version = "0.31.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d277279d0a3b0c0021dd110b55aa1fe326b09ee2cbc338df28f847c7daf94e25"
+checksum = "ce3cdfe5e46c3f39d2d51bb6d6e5771347021889c5f6a7cade8ff7c401ccfbd7"
 dependencies = [
  "accesskit",
  "accesskit_consumer",
@@ -849,6 +852,12 @@ version = "1.0.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e5464a87b239f13a63a501f2701565754bae92d243d4bb7eb12f6d57d2269bf4"
 
+[[package]]
+name = "uuid"
+version = "1.19.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e2e054861b4bd027cd373e18e8d8d8e6548085000e41290d95ce0c373a654b4a"
+
 [[package]]
 name = "winapi"
 version = "0.3.9"
diff --git a/Cargo.toml b/Cargo.toml
index 8e510a6..c306fe5 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -16,16 +16,16 @@ doc = false
 cbindgen = []
 
 [dependencies]
-accesskit = "0.22.0"
+accesskit = "0.23.0"
 
 [target.'cfg(target_os = "windows")'.dependencies]
-accesskit_windows = "0.30.0"
+accesskit_windows = "0.31.1"
 
 [target.'cfg(target_os = "macos")'.dependencies]
-accesskit_macos = "0.23.0"
+accesskit_macos = "0.24.1"
 
 [target.'cfg(any(target_os = "linux", target_os = "dragonfly", target_os = "freebsd", target_os = "openbsd", target_os = "netbsd"))'.dependencies]
-accesskit_unix = "0.18.0"
+accesskit_unix = "0.19.1"
 
 [profile.release]
 lto = true
diff --git a/cbindgen.toml b/cbindgen.toml
index f28984a..824ef6e 100644
--- a/cbindgen.toml
+++ b/cbindgen.toml
@@ -54,6 +54,7 @@ renaming_overrides_prefixing = true
 "SortDirection" = "accesskit_sort_direction"
 "TextAlign" = "accesskit_text_align"
 "TextDecoration" = "accesskit_text_decoration"
+"TextDecorationStyle" = "accesskit_text_decoration_style"
 "TextDirection" = "accesskit_text_direction"
 "Toggled" = "accesskit_toggled"
 "Vec2" = "accesskit_vec2"
diff --git a/examples/sdl/hello_world.c b/examples/sdl/hello_world.c
index 9deb453..d2dcb04 100644
--- a/examples/sdl/hello_world.c
+++ b/examples/sdl/hello_world.c
@@ -262,7 +262,7 @@ void do_action(accesskit_action_request *request, void *userdata) {
   SDL_zero(event);
   event.type = state->event_type;
   event.user.windowID = state->window_id;
-  event.user.data1 = (void *)((uintptr_t)(request->target));
+  event.user.data1 = (void *)((uintptr_t)(request->target_node));
   if (request->action == ACCESSKIT_ACTION_FOCUS) {
     event.user.code = SET_FOCUS_MSG;
     SDL_PushEvent(&event);
diff --git a/examples/windows/hello_world.c b/examples/windows/hello_world.c
index 06e96e5..951e595 100644
--- a/examples/windows/hello_world.c
+++ b/examples/windows/hello_world.c
@@ -86,10 +86,10 @@ accesskit_tree_update *build_initial_tree(void *userdata) {
 void do_action(accesskit_action_request *request, void *userdata) {
   HWND window = userdata;
   if (request->action == ACCESSKIT_ACTION_FOCUS) {
-    LPARAM lparam = (LPARAM)(request->target);
+    LPARAM lparam = (LPARAM)(request->target_node);
     PostMessage((HWND)window, SET_FOCUS_MSG, 0, lparam);
   } else if (request->action == ACCESSKIT_ACTION_CLICK) {
-    LPARAM lparam = (LPARAM)(request->target);
+    LPARAM lparam = (LPARAM)(request->target_node);
     PostMessage((HWND)window, DO_DEFAULT_ACTION_MSG, 0, lparam);
   }
   accesskit_action_request_free(request);
diff --git a/include/accesskit.h b/include/accesskit.h
index 8df227f..227a974 100644
--- a/include/accesskit.h
+++ b/include/accesskit.h
@@ -515,19 +515,19 @@ enum accesskit_text_align
 typedef uint8_t accesskit_text_align;
 #endif  // __cplusplus
 
-enum accesskit_text_decoration
+enum accesskit_text_decoration_style
 #ifdef __cplusplus
     : uint8_t
 #endif  // __cplusplus
 {
-  ACCESSKIT_TEXT_DECORATION_SOLID,
-  ACCESSKIT_TEXT_DECORATION_DOTTED,
-  ACCESSKIT_TEXT_DECORATION_DASHED,
-  ACCESSKIT_TEXT_DECORATION_DOUBLE,
-  ACCESSKIT_TEXT_DECORATION_WAVY,
+  ACCESSKIT_TEXT_DECORATION_STYLE_SOLID,
+  ACCESSKIT_TEXT_DECORATION_STYLE_DOTTED,
+  ACCESSKIT_TEXT_DECORATION_STYLE_DASHED,
+  ACCESSKIT_TEXT_DECORATION_STYLE_DOUBLE,
+  ACCESSKIT_TEXT_DECORATION_STYLE_WAVY,
 };
 #ifndef __cplusplus
-typedef uint8_t accesskit_text_decoration;
+typedef uint8_t accesskit_text_decoration_style;
 #endif  // __cplusplus
 
 enum accesskit_text_direction
@@ -625,6 +625,24 @@ typedef struct accesskit_opt_node_id {
   accesskit_node_id value;
 } accesskit_opt_node_id;
 
+/**
+ * A 128-bit identifier for a tree, represented as a UUID in big-endian byte
+ * order.
+ */
+typedef struct accesskit_tree_id {
+  uint8_t bytes[16];
+} accesskit_tree_id;
+
+/**
+ * Represents an optional value.
+ *
+ * If `has_value` is false, do not read the `value` field.
+ */
+typedef struct accesskit_opt_tree_id {
+  bool has_value;
+  struct accesskit_tree_id value;
+} accesskit_opt_tree_id;
+
 /**
  * Represents an optional value.
  *
@@ -675,6 +693,14 @@ typedef struct accesskit_opt_color {
   struct accesskit_color value;
 } accesskit_opt_color;
 
+/**
+ * The style and color for a type of text decoration.
+ */
+typedef struct accesskit_text_decoration {
+  accesskit_text_decoration_style style;
+  struct accesskit_color color;
+} accesskit_text_decoration;
+
 /**
  * Represents an optional value.
  *
@@ -682,7 +708,7 @@ typedef struct accesskit_opt_color {
  */
 typedef struct accesskit_opt_text_decoration {
   bool has_value;
-  accesskit_text_decoration value;
+  struct accesskit_text_decoration value;
 } accesskit_opt_text_decoration;
 
 typedef struct accesskit_lengths {
@@ -963,7 +989,8 @@ typedef struct accesskit_opt_action_data {
 
 typedef struct accesskit_action_request {
   accesskit_action action;
-  accesskit_node_id target;
+  struct accesskit_tree_id target_tree;
+  accesskit_node_id target_node;
   struct accesskit_opt_action_data data;
 } accesskit_action_request;
 
@@ -1036,6 +1063,8 @@ typedef struct accesskit_opt_lresult {
 extern "C" {
 #endif  // __cplusplus
 
+extern const struct accesskit_tree_id ACCESSKIT_TREE_ID_ROOT;
+
 accesskit_role accesskit_node_role(const struct accesskit_node *node);
 
 void accesskit_node_set_role(struct accesskit_node *node, accesskit_role value);
@@ -1354,6 +1383,14 @@ void accesskit_node_set_popup_for(struct accesskit_node *node,
 
 void accesskit_node_clear_popup_for(struct accesskit_node *node);
 
+struct accesskit_opt_tree_id accesskit_node_tree_id(
+    const struct accesskit_node *node);
+
+void accesskit_node_set_tree_id(struct accesskit_node *node,
+                                struct accesskit_tree_id value);
+
+void accesskit_node_clear_tree_id(struct accesskit_node *node);
+
 /**
  * Only call this function with a string that originated from AccessKit.
  */
@@ -1932,7 +1969,7 @@ struct accesskit_opt_text_decoration accesskit_node_overline(
     const struct accesskit_node *node);
 
 void accesskit_node_set_overline(struct accesskit_node *node,
-                                 accesskit_text_decoration value);
+                                 struct accesskit_text_decoration value);
 
 void accesskit_node_clear_overline(struct accesskit_node *node);
 
@@ -1940,7 +1977,7 @@ struct accesskit_opt_text_decoration accesskit_node_strikethrough(
     const struct accesskit_node *node);
 
 void accesskit_node_set_strikethrough(struct accesskit_node *node,
-                                      accesskit_text_decoration value);
+                                      struct accesskit_text_decoration value);
 
 void accesskit_node_clear_strikethrough(struct accesskit_node *node);
 
@@ -1948,7 +1985,7 @@ struct accesskit_opt_text_decoration accesskit_node_underline(
     const struct accesskit_node *node);
 
 void accesskit_node_set_underline(struct accesskit_node *node,
-                                  accesskit_text_decoration value);
+                                  struct accesskit_text_decoration value);
 
 void accesskit_node_clear_underline(struct accesskit_node *node);
 
@@ -2263,6 +2300,12 @@ void accesskit_tree_update_clear_tree(struct accesskit_tree_update *update);
 void accesskit_tree_update_set_focus(struct accesskit_tree_update *update,
                                      accesskit_node_id focus);
 
+struct accesskit_tree_id accesskit_tree_update_get_tree_id(
+    const struct accesskit_tree_update *update);
+
+void accesskit_tree_update_set_tree_id(struct accesskit_tree_update *update,
+                                       struct accesskit_tree_id tree_id);
+
 /**
  * Caller must call `accesskit_string_free` with the return value.
  */
diff --git a/src/common.rs b/src/common.rs
index d94636e..3cb9dfb 100644
--- a/src/common.rs
+++ b/src/common.rs
@@ -194,6 +194,29 @@ macro_rules! vec_property_methods {
 
 pub type node_id = u64;
 
+/// A 128-bit identifier for a tree, represented as a UUID in big-endian byte order.
+#[repr(C)]
+pub struct tree_id {
+    pub bytes: [u8; 16],
+}
+
+impl From<TreeId> for tree_id {
+    fn from(id: TreeId) -> Self {
+        Self {
+            bytes: *id.0.as_bytes(),
+        }
+    }
+}
+
+impl From<tree_id> for TreeId {
+    fn from(id: tree_id) -> Self {
+        TreeId(Uuid::from_bytes(id.bytes))
+    }
+}
+
+#[no_mangle]
+pub static ACCESSKIT_TREE_ID_ROOT: tree_id = tree_id { bytes: [0; 16] };
+
 slice_struct! { node_ids, NodeId, node_id }
 
 macro_rules! node_id_vec_property_methods {
@@ -468,6 +491,12 @@ node_id_property_methods! {
     (accesskit_node_popup_for, popup_for, accesskit_node_set_popup_for, set_popup_for, accesskit_node_clear_popup_for, clear_popup_for)
 }
 
+opt_struct! { opt_tree_id, tree_id }
+
+simple_property_methods! {
+    accesskit_node_tree_id, tree_id, opt_tree_id, accesskit_node_set_tree_id, set_tree_id, tree_id, accesskit_node_clear_tree_id, clear_tree_id
+}
+
 /// Only call this function with a string that originated from AccessKit.
 #[no_mangle]
 pub extern "C" fn accesskit_string_free(string: *mut c_char) {
@@ -938,6 +967,7 @@ impl tree_update {
         let update = TreeUpdate {
             nodes: vec![],
             tree: None,
+            tree_id: TreeId::ROOT,
             focus: focus.into(),
         };
         BoxCastPtr::to_mut_ptr(update)
@@ -951,6 +981,7 @@ impl tree_update {
         let update = TreeUpdate {
             nodes: Vec::with_capacity(capacity),
             tree: None,
+            tree_id: TreeId::ROOT,
             focus: focus.into(),
         };
         BoxCastPtr::to_mut_ptr(update)
@@ -992,6 +1023,21 @@ impl tree_update {
         update.focus = focus.into();
     }
 
+    #[no_mangle]
+    pub extern "C" fn accesskit_tree_update_get_tree_id(update: *const tree_update) -> tree_id {
+        let update = ref_from_ptr(update);
+        update.tree_id.into()
+    }
+
+    #[no_mangle]
+    pub extern "C" fn accesskit_tree_update_set_tree_id(
+        update: *mut tree_update,
+        tree_id: tree_id,
+    ) {
+        let update = mut_from_ptr(update);
+        update.tree_id = tree_id.into();
+    }
+
     /// Caller must call `accesskit_string_free` with the return value.
     #[no_mangle]
     pub extern "C" fn accesskit_tree_update_debug(tree_update: *const tree_update) -> *mut c_char {
@@ -1042,7 +1088,8 @@ impl From<ActionData> for action_data {
 #[repr(C)]
 pub struct action_request {
     pub action: Action,
-    pub target: node_id,
+    pub target_tree: tree_id,
+    pub target_node: node_id,
     pub data: opt_action_data,
 }
 
@@ -1050,7 +1097,8 @@ impl From<ActionRequest> for action_request {
     fn from(request: ActionRequest) -> action_request {
         Self {
             action: request.action,
-            target: request.target.into(),
+            target_tree: request.target_tree.into(),
+            target_node: request.target_node.into(),
             data: request.data.into(),
         }
     }