Inconveniencing with Mdiparent while updating Mdiparent after Load

=] eheh. Thank you for complimenting. But compared to others in this domain of software development, I am just starting. But this is what I believe in coding. There is nothing like you know to 'code'. For a fact, I do not even remember any coding. All I do remember is the basics of programming and understanding how they really work. For coding, all I do is solve a given problem logically and write down the logic I came up with. In case I do not know how to code my logic I read books or ask someone with more experience or of course, google it.
So on to your question, it is a basic rule in C# that any variable must be initialized prior using it. I.e. if you create a variable, you need to initialize it to a value prior using it anywhere in your code. Now in this case, I have initialized the "mdiParent" variable in to 'null' which means nothing. Just think logically what would happen if you call a method like "show()" on nothing ? Doesn't make any sense even right? So you need to initialize the variable with a new "MdiParent1" object.
Now think about two methods which use this "mdiParent" variable. In the method 1, you have the initialize variable code. In the method 2, you don't have it because, method 2 will never be called before method 1 according to the way you code. But think you decide to work on your code after 2 years and you accidentally call method 2 before calling method 1. Now when the method 2 is called, is the variable initialized ? No, right ? So that's why you always check whether a variable is null before using it.
Hope this clarifies your doubt.