<p>Say if I have a dropdown in a form and I have another nested class inside of this class .
Now what's the best way to access this dropdown from the nested class? </p>

Unlike Java, a nested class isn't a special "inner class" so you'd need to pass a reference.  Raymond Chen has an example describing the differences here :
C# nested classes are like C++ nested classes, not Java inner classes
.
Here is an example where the constructor of the nested class is passed the instance of the outer class for later reference.
```
```
// C#
class OuterClass 
{
    string s;
    // ...
    class InnerClass 
    {
       OuterClass o_;
       public InnerClass(OuterClass o) { o_ = o; }
       public string GetOuterString() { return o_.s; }
    }
    void SomeFunction() {
        InnerClass i = new InnerClass(this);
        i.GetOuterString();
    }

}
```
```
Note that the InnerClass can access the "
```
s
```
" of the OuterClass, I didn't modify Raymond's code (as I linked to above), so remember that the "
```
string s;
```
" is
```
private
```
because no other access permission was specified.