Question: I have a main form and a user control(with graphs). And I'm updating the graphs dynamically. 

```
 void foo(int i)
        {

            MainForm MF = (MainForm)MainForm.ActiveForm;
            if (tb != null)
            {
                tb.userGraph.updatesomething(i);
               // usergraph is the user control which has graphs
            }

        }

```

The problem is when I navigate out of the main form I cant update the graph. Is there any other way where I can write into the user control even if its not the active form?
If I create a new instance, the previous updates on the graph will be gone.

Answer: 
Use [InsertRange](http://msdn.microsoft.com/en-us/library/884ee1fz.aspx) method:

```
 myList.InsertRange(0, moreItems);

```
```
List<String> listA=new List<String>{"A","B","C"};
List<String> listB=new List<String>{"p","Q","R"};

listA.InsertRange(0, listB);    

```

Here suppose we have 2 list of string... then using the InsertRange method we can pass the starting index where we want to insert/push the new range(listB) to the existing range(listA)

Hope this clears the code.