Introduction

You can then select one of the preset colors from 3 windows represented with tabs:

As you can see, the System and the Web tabs provide colors by name. All regular names of colors of the English language are represented. If you have done Windows programming before, you may recognize the names of colors in the System tab because they are the same names you would see in Control Panel, except that the names are in one word. If you have done web development before, you may recognize the names because they are the same defined by Netscape. The names in both the System and the Web tabs are defined in an enumeration called Color.

If you are not familiar with the names of colors, you can visually select a color in the Custom tab.

To programmatically specify the background color of a control, access its BackColor property and assign it the desired member of the Color enumeration. Here is an example:

Imports System
Imports System.Drawing
Imports System.Windows.Forms

Module Exercise

    Public Class WinControls
        Inherits Form

        Private btnSubmit As Button

        Dim components As System.ComponentModel.Container

        Public Sub New()
            InitializeComponent()
        End Sub

        Public Sub InitializeComponent()
            btnSubmit = New Button()
            btnSubmit.Text = "Submit"
            btnSubmit.Location = New Point(20, 20)
            btnSubmit.Size = New Size(100, 60)

            btnSubmit.BackColor = Color.Aquamarine

            Controls.Add(btnSubmit)
        End Sub

        Public Shared Function Main() As Integer

            Application.Run(New WinControls())
            Return 0

        End Function

    End Class

End Module

Instead of a color, you may want to fill the control with a picture. To do this, you can access the control's BackgroundImage property. This provides an ellipsis button you can use to locate and select the desired picture.

Some controls display a border when they are drawn and some others don't. Consider the following:

Some of these controls allow you to specify a type of border you want to show surrounding the controls. This characteristic is controlled by the BorderStyle property, which is based on BorderStyle enumerator. Its members are:

Value	Example
Fixed3D
FixedSingle
None

To programmatically specify the border style of a control, access its BorderStyle property and assign it the desired BorderStyle member. Here is an example:

Imports System
Imports System.Drawing
Imports System.Windows.Forms

Module Exercise

    Public Class WinControls
        Inherits Form

        Private pnlViewer As Panel

        Dim components As System.ComponentModel.Container

        Public Sub New()
            InitializeComponent()
        End Sub

        Public Sub InitializeComponent()

            pnlViewer = New Panel()
            pnlViewer.BorderStyle = BorderStyle.Fixed3D
            pnlViewer.BackColor = Color.LightBlue
            Controls.Add(pnlViewer)

        End Sub

        Public Shared Function Main() As Integer

            Application.Run(New WinControls())
            Return 0

        End Function

    End Class

End Module

A user can navigate through controls using the Tab key. When that key has been pressed, the focus moves from one control to the next. By their designs, not all controls can receive focus and not all controls can participate in tab navigation. Even controls that can receive focus must be primarily included in the tab sequence.

At design time, the participation to tab sequencing is controlled by the Boolean TabStop property in the Properties window. Every visual control that can receive focus is already configured to have this property set to True. If you want to remove a control from this sequence, set its TabStop value to False.

If a control has the TabStop property set to True, to arrange the navigation order of controls, you have two main options. At design time, you can click a control on the form. Then, on the Properties window, change the value of its TabIndex field. The value must be a positive short integer.

The best and easiest way to arrange the tab sequence of controls is to manage it visually. To do this, first display the form. Then, on the main menu, click View. This causes a number to be positioned on every control of the form. Here is an example:

To arrange the sequence any way you like, click each control once in the desired order. Normally, static controls (such as the label, the picture box, the panel, etc) never receive focus when the application is running; therefore, you can skip such controls.

1. Click anywhere in the form
2. On the main menu, click View -> Tab Order
3. On the form, click, in the following order, the text box on the right side of Length, the text box on the right side of Height, the Calculate button, and the Close button
    
   
4. Press Esc to dismiss the Tab Order tool
5. On the form, click the text box on the right side of Perimeter:
6. In the Properties window, set the TabStop to False
    
   
7. In the same way, set the TabStop property of the text box on the right side of Area: to False
8. Execute the application
9. Press Tab a few times and observe the behavior
10. Close the form and return to your programming environment

A control is referred to as visible if it can be visually located on the screen. A user can use a control only if he or she can see it. As a programmer, you have the role of deciding whether a control must be seen or not and when. The visibility of an object is controlled by the its Visible property. This is a Boolean property.

At design time, when you add a control to a parent, it is visible by default. This is because its Visible property is set to True in the Properties window. In the same way, if you programmatically create a control, by default, it is made visible once you add it to its parent's Controls property.

If you don't want a control to primarily appear when the form comes up, you can either set its Visible property to False or set its parent’s visible property to False. Equivalently, at run time, to hide a control, assign a False value to either its Visible property or its parent’s Visible property. Keep in mind that when a parent gets hidden, it also hides its children. On the other hand, a parent can be made visible but hide one or some of its children.

To programmatically check whether a control is visible at one time, apply a conditional statement (if or while) to its Visible property and check whether its value is true or false.

For the user to use a control, it must allow operations on it. For example, if a control is supposed to receive text, the user can enter characters in it only if this is made possible. To make a control available to the user, the object must be enabled. The availability of an object is controlled by the Boolean Enabled property.

By default, after adding a control to a form, it is enabled and its Enabled property in the Properties window is set to True. An enabled control displays its text or other characteristics in their normal settings. If you want to disable a control, set its Enabled property to False. In the following picture, a text box and a button are disabled:

To programmatically find out whether a control is enabled or not, check its Enabled property.