Added DockState::iter_nodes_mut and DockState::iter_main_surface_node…

…s_mut (#195)

* added iter_nodes_mut

* finished adding iter_nodes_mut

* added iter_main_surface_nodes_mut

* ran cargo fmt

src/dock_state/mod.rs

@@ -379,13 +379,26 @@ impl<Tab> DockState<Tab> {
         self[SurfaceIndex::main()].iter()
     }
 
+    /// Returns a mutable `Iterator` of the underlying collection of nodes on the main surface.
+    pub fn iter_main_surface_nodes_mut(&mut self) -> std::slice::IterMut<'_, Node<Tab>> {
+        self[SurfaceIndex::main()].iter_mut()
+    }
+
     /// Returns an `Iterator` of **all** underlying nodes in the dock state and all subsequent trees.
     pub fn iter_nodes(&self) -> impl Iterator<Item = &Node<Tab>> {
         self.surfaces
             .iter()
             .filter_map(|tree| tree.node_tree())
             .flat_map(|nodes| nodes.iter())
     }
+
+    /// Returns a mutable `Iterator` of **all** underlying nodes in the dock state and all subsequent trees.
+    pub fn iter_nodes_mut(&mut self) -> impl Iterator<Item = &mut Node<Tab>> {
+        self.surfaces
+            .iter_mut()
+            .filter_map(|tree| tree.node_tree_mut())
+            .flat_map(|nodes| nodes.iter_mut())
+    }
 }
 
 impl<Tab> DockState<Tab>