Let a canvas::Program control the mouse cursor

wgpu/src/widget/canvas.rs

@@ -210,7 +210,7 @@ impl<Message, P: Program<Message>> Widget<Message, Renderer>
                         .collect(),
                 }),
             },
-            MouseCursor::Idle,
+            self.program.mouse_cursor(size),
         )
     }
 

wgpu/src/widget/canvas/program.rs

@@ -1,4 +1,5 @@
 use crate::canvas::{Event, Geometry, Size};
+use iced_native::MouseCursor;
 
 pub trait Program<Message> {
     fn update(&mut self, _event: Event, _bounds: Size) -> Option<Message> {
@@ -6,6 +7,10 @@ pub trait Program<Message> {
     }
 
     fn draw(&self, bounds: Size) -> Vec<Geometry>;
+
+    fn mouse_cursor(&self, _bounds: Size) -> MouseCursor {
+        MouseCursor::default()
+    }
 }
 
 impl<T, Message> Program<Message> for &mut T
@@ -19,4 +24,8 @@ where
     fn draw(&self, bounds: Size) -> Vec<Geometry> {
         T::draw(self, bounds)
     }
+
+    fn mouse_cursor(&self, bounds: Size) -> MouseCursor {
+        T::mouse_cursor(self, bounds)
+    }
 }