Hi there,

Recently, I've upgraded to the 2.7.3 version, where I also contributed via this attached PR.

Unfortunately, the leak was not resolved, even with my above contribution. I'll try to explain the reason for that.

In order to reproduce, you can just chose a random class and add in the constructor / some initialization method the following lines:

Binding.AddPropertyEvent(viewModel, vm => vm.Checked, OnCheckedChanged);
Binding.RemovePropertyEvent(viewModel, OnCheckedChanged);

Expected Behavior

After writing the above lines, we expect the OnCheckedChanged event handler to never be invoked, as we don't have a subscription to it, as we've invoked Binding.RemovePropertyEvent for it.

Actual Behavior

The OnCheckedChanged event handler is still invoked, even after calling Binding.RemovePropertyEvent for it (the breakpoint is hit).

Specifications

• Version: 2.7.3
• Platform(s): WPF
• Operating System(s): Windows 10, Windows 11

Reason for the issue:

In 2.7.3, your source code for the Binding.RemovePropertyEvent looks as following:

public static void RemovePropertyEvent(object obj, EventHandler<EventArgs> eh)
{
	var helper = eh.Target as PropertyNotifyHelper;
	if (helper != null)
	{
		helper.Changed -= eh;
		helper.Unregister(obj);
	}
}

Previously, I've contributed by adding the helper.Changed -= eh; line, but surprisingly, as I've mentioned, the leak is still there, and the event handler keeps getting invoked, even after calling this RemovePropertyEvent method.

After investigating a bit, I've discovered that the helper is null, because eh.Target is not of type PropertyNotifyHelper , but of the type of the class, where I've defined the event handler (i.e. CustomCheckBox.cs). Thus, this code:

helper.Changed -= eh;
helper.Unregister(obj);

never happens, and the subscription is kept alive.

I couldn't find any issue about it, so was wondering if you are aware of that.

A possible direction is to understand why eh.Target stopped working for WPF (assuming it used to work).