runtime: Remove start_dnd

This is not currently used. And is impossible to (soundly) use, since it
requires a `Send` bound, which `State` and `Element` lack.

Cargo.lock

@@ -3218,11 +3218,13 @@ dependencies = [
  "mundy",
  "raw-window-handle",
  "rustc-hash 2.1.1",
+ "rustix 0.38.44",
  "sysinfo",
  "thiserror 2.0.17",
  "tracing",
  "wasm-bindgen-futures",
  "wayland-backend",
+ "wayland-client",
  "wayland-protocols 0.32.9",
  "web-sys",
  "winapi",

runtime/src/dnd.rs

@@ -17,19 +17,6 @@ pub enum DndAction {
         /// The rectangles to register.
         rectangles: Vec<DndDestinationRectangle>,
     },
-    /// Start a Dnd operation.
-    StartDnd {
-        /// Whether the Dnd operation is internal.
-        internal: bool,
-        /// The source surface of the Dnd operation.
-        source_surface: Option<DndSource>,
-        /// The icon surface of the Dnd operation.
-        icon_surface: Option<Box<dyn Any + Send>>,
-        /// The content of the Dnd operation.
-        content: Box<dyn AsMimeTypes + Send + 'static>,
-        /// The actions of the Dnd operation.
-        actions: dnd::DndAction,
-    },
     /// End a Dnd operation.
     EndDnd,
     /// Peek the current Dnd operation.
@@ -53,19 +40,6 @@ impl std::fmt::Debug for DndAction {
                 .field("surface", surface)
                 .field("rectangles", rectangles)
                 .finish(),
-            Self::StartDnd {
-                internal,
-                source_surface,
-                icon_surface,
-                content: _,
-                actions,
-            } => f
-                .debug_struct("StartDnd")
-                .field("internal", internal)
-                .field("source_surface", source_surface)
-                .field("icon_surface", icon_surface)
-                .field("actions", actions)
-                .finish(),
             Self::EndDnd => f.write_str("EndDnd"),
             Self::PeekDnd(mime, _) => {
                 f.debug_struct("PeekDnd").field("mime", mime).finish()
@@ -99,23 +73,6 @@ pub fn register_dnd_destination<Message>(
     }))
 }
 
-/// Start a Dnd operation.
-pub fn start_dnd<Message>(
-    internal: bool,
-    source_surface: Option<DndSource>,
-    icon_surface: Option<Box<dyn Any + Send>>,
-    content: Box<dyn AsMimeTypes + Send + 'static>,
-    actions: dnd::DndAction,
-) -> Task<Message> {
-    task::effect(Action::Dnd(DndAction::StartDnd {
-        internal,
-        source_surface,
-        icon_surface,
-        content,
-        actions,
-    }))
-}
-
 /// End a Dnd operation.
 pub fn end_dnd<Message>() -> Task<Message> {
     task::effect(Action::Dnd(DndAction::EndDnd))

winit/src/lib.rs

@@ -2170,15 +2170,6 @@ where
             iced_runtime::dnd::DndAction::SetAction(a) => {
                 clipboard.set_action(a);
             }
-            iced_runtime::dnd::DndAction::StartDnd {
-                internal,
-                source_surface,
-                icon_surface,
-                content,
-                actions,
-            } => {
-                // removed
-            }
         },
         Action::PlatformSpecific(a) => {
             platform_specific.send_action(a);