I have noticed the Tag properties with controls. Is it okay to use this to reference my custom objects, or should I stay away from it as it would require boxing and unboxing which has been mentioned as unsafe and is not recommended.
TreeNode tn = new TreeNode();
CustClass o = new CustClass()
o.number = 123;
tn.Tag = o;
class CustClass
{
public int number {get; set;}
}
The purpose of the Tag property is for you to use it for any purpose you want. You can safely store anything in there you want.
It is customary to declare a class that is specifically intended for being stored in the Tag property (like you did with your CustClass). But if you need only one value in it, then there is nothing wrong with storing an int in it directly.
Where did you read that boxing/unboxing is “unsafe”? That is absolutely not true. (Some people claim that it is inefficient, but even that is not true.) Furthermore, your code does not even contain an example of boxing at all. CustClass is a reference type. Only value types are boxed when assigned to object.