Fix Garbage Collection of Delegates

Libs/GObject/Classes/ClosureHelper.cs

@@ -12,6 +12,10 @@ internal class ClosureHelper : IDisposable
 
         private static readonly Dictionary<Delegate, ClosureHelper> Handlers = new Dictionary<Delegate, ClosureHelper>();
 
+        // We need to store a reference to MarshalCallback to
+        // prevent the delegate from being collected by the GC
+        private readonly ClosureMarshal _marshalCallback;
+
         private bool _disposedValue;
         private readonly Action? _callback;
         private readonly ActionRefValues? _callbackRefValues;
@@ -41,7 +45,8 @@ public ClosureHelper(Object obj, ActionRefValues callbackRefValues) : this(obj)
         private ClosureHelper(Object obj)
         {
             Handle = Closure.Native.new_object((uint) Marshal.SizeOf(typeof(Closure)), obj.Handle);
-            Closure.Native.set_marshal(Handle, MarshalCallback);
+            _marshalCallback = MarshalCallback;
+            Closure.Native.set_marshal(Handle, _marshalCallback);
         }
 
         ~ClosureHelper() => Dispose(false);
@@ -50,12 +55,12 @@ private ClosureHelper(Object obj)
 
         #region Methods
 
-        private void MarshalCallback(IntPtr closure, ref Value return_value, uint n_param_values,
-            Value[] param_values, IntPtr invocation_hint, IntPtr marshal_data)
+        private void MarshalCallback(IntPtr closure, ref Value returnValue, uint nParamValues,
+            Value[] paramValues, IntPtr invocationHint, IntPtr marshalData)
         {
             _callback?.Invoke();
 
-            _callbackRefValues?.Invoke(ref param_values);
+            _callbackRefValues?.Invoke(ref paramValues);
         }
 
         public static bool TryGetByDelegate(Action action, out ClosureHelper closure)

Libs/GObject/Classes/Object.cs

@@ -27,6 +27,10 @@ public partial class Object : INotifyPropertyChanged, IDisposable
         #region Properties
 
         protected internal IntPtr Handle { get; private set; }
+
+        // We need to store a reference to WeakNotify to
+        // prevent the delegate from being collected by the GC
+        private WeakNotify? _onFinalized;
 
         protected bool Disposed { get; private set; }
 
@@ -135,7 +139,11 @@ protected virtual void Initialize() { }
 
         // Modify this in the future to play nicely with virtual function support?
         private void OnFinalized(IntPtr data, IntPtr where_the_object_was) => Dispose();
-        private void RegisterOnFinalized() => Native.weak_ref(Handle, OnFinalized, IntPtr.Zero);
+        private void RegisterOnFinalized()
+        {
+            _onFinalized = OnFinalized;
+            Native.weak_ref(Handle, _onFinalized, IntPtr.Zero);
+        }
 
         private void RegisterProperties()
         {
@@ -182,9 +190,7 @@ private void RegisterEvent(string eventName, ClosureHelper closure, bool after)
             if (ret == 0)
                 throw new Exception($"Could not connect to event {eventName}");
 
-            // Add to our closures list so the callback
-            // doesn't get garbage collected.
-            // closures.Add(closure);
+            // Add to our closures list so the callback doesn't get garbage collected.
             Closures[closure] = ret;
         }