C# 4 and .NET 4

Working with Visual studio 2010 ❘ 391
In one sense, there is no difference between the code editor and the design view; they simply present
different views of the same code. What actually happened when you clicked to add the TextBox to the
design view is that the editor placed the preceding extra code in your C# source fi le for you. The design
view simply refl ects this change because Visual Studio is able to read your source code and determine from
it what controls should be around when the application starts up. This is a fundamental shift from the old
Visual Basic way of looking at things, in which everything was based around the visual design. Now, your
C# source code is what fundamentally controls your application, and the design view is just a different way
of viewing the source code. Incidentally, if you do write any Visual Basic 2010 code with Visual Studio, you
will fi nd the same principles at work.
If you had wanted to, you could have worked the other way around. If you had manually added the
same code to your C# source fi les, Visual Studio would have automatically detected from the code that
your application contained a TextBox control and would have shown it in the design view at the
designated position. It is best to add these controls visually, and let Visual Studio handle the initial code
generation — it is a lot quicker and less error - prone to click the mouse button a couple of times than to type
a few lines of code!
Another reason for adding these controls visually is that, to recognize that they are there, Visual Studio does
need the relevant code to conform to certain criteria — and code that you write by hand might not do so.
In particular, you will notice that the InitializeComponent() method that contains the code to initialize
the TextBox is commented to warn you against modifying it. That is because this is the method that Visual
Studio looks at to determine what controls are around when your application starts up. If you create and
defi ne a control somewhere else in your code, Visual Studio will not be aware of it, and you will not be able
to edit it in the design view or in certain other useful windows.
In fact, despite the warnings, you can modify the code in InitializeComponent() , provided that you are
careful. There is generally no harm in changing the values of some of the properties, for example, so that a
control displays different text or so that it is a different size. In practice, the developer studio is pretty robust
when it comes to working around any other code you place in this method. Just be aware that if you make
too many changes to InitializeComponent() , you do run the risk that Visual Studio will not recognize
some of your controls. We should stress that this will not affect your application in any way whatsoever
when it is compiled, but it might disable some of the editing features of Visual Studio for those controls.
Hence, if you want to add any other substantial initialization, it is probably better to do so in the Form1
constructor or in some other method.
The Properties Window
This is another window that has its origins in the old Visual Basic IDE. You know from the fi rst part of
the book that .NET classes can implement properties. In fact, as you will discover when building Windows
Forms (see Chapter 39), the .NET base classes that represent forms and controls have a lot of properties
that defi ne their action or appearance — properties such as Width , Height , Enabled (whether the user can
type input to the control), and Text (the text displayed by the control) — and Visual Studio knows about
many of these properties. The Properties window, shown in Figure 16 - 19, appears and allows you to edit
the initial values of most of these properties for the controls that Visual Studio has been able to detect by
reading your source code.
The Properties window can also show events. You can view events for what you are
focused on in the IDE or selected in the drop-down list box directly in the Properties
window by clicking the icon that looks like a lightning bolt at the top of the window.
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