Label

Labels are those controls that are used to display text in other parts of the application. They are based on the Control class.

Notable property of the label control is the text property which is used to set the text for the label.

Label Event

The default event of Label is the Click event which looks like this in code:

Private Sub Label1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)_
Handles Label1.Click

End Sub

Creating a Label in Code

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs)_
Handles MyBase.Load Dim Label1 As New Label()
Label1.Text = "Label"
Label1.Location = New Point(135, 70)
Label1.Size = New Size(30, 30)
Me.Controls.Add(Label1)
End Sub

LinkLabel

LinkLabel is similar to a Label but they display a hyperlink. Even multiple hyperlinks can be specified in the text of the control and each hyperlink can perform a different task within the application. They are based on the Label class which is based on the Control class.

Notable properties of the LinkLabel control are the ActiveLinkColor, LinkColor and LinkVisited which are used to set the link color.

LinkLabel Event

The default event of LinkLabel is the LinkClicked event which looks like this in code:

Private Sub LinkLabel1_LinkClicked(ByVal sender As System.Object, _
ByVal e As System.Windows.Forms.LinkLabelLinkClickedEventArgs)_
Handles LinkLabel1.LinkClicked

End Sub

Working with LinkLabel

Private Sub LinkLabel1_LinkClicked(ByVal sender As System.Object, ByVal_
e As System.Windows.Forms.LinkLabelLinkClickedEventArgs)_
Handles LinkLabel1.LinkClicked
System.Diagnostics.Process.Start("www.mls.com.np")
'using the start method of system.diagnostics.process class
'process class gives access to local and remote processes
End Sub

Creating a LinkLabel in Code

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs)_
Handles MyBase.Load
Dim LinkLabel1 As New LinkLabel()
LinkLabel1.Text = "Label"
LinkLabel1.Location = New Point(135, 70)
LinkLabel1.Size = New Size(30, 30)
Me.Controls.Add(LinkLabel1)
End Sub

*************************************************************************

TextBox

Windows users should be familiar with textboxes. This control looks like a box and accepts input from the user. The TextBox is based on the TextBoxBase class which is based on the Control class. TextBoxes are used to accept input from the user or used to display text. By default we can enter up to 2048 characters in a TextBox but if the Multiline property is set to True we can enter up to 32KB of text.

Some important properties in the Behavior section of the Properties Window for TextBoxes.

Enabled: Default value is True. To disable, set the property to False.
Multiline: Setting this property to True makes the TextBox multiline which allows to accept multiple lines of text. Default value is False.
PasswordChar: Used to set the password character. The text displayed in the TextBox will be the character set by the user. Say, if you enter *, the text that is entered in the TextBox is displayed as *.
ReadOnly: Makes this TextBox readonly. It doesn't allow to enter any text.
Visible: Default value is True. To hide it set the property to False.

Important properties in the Appearance section

TextAlign: Allows to align the text from three possible options. The default value is left and you can set the alignment of text to right or center.
Scrollbars: Allows to add a scrollbar to a Textbox. Very useful when the TextBox is multiline. You have four options with this property. Options are are None, Horizontal, Vertical and Both. Depending on the size of the TextBox anyone of those can be used.

TextBox Event

The default event of the TextBox is the TextChanged Event which looks like this in code:

Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As _
System.EventArgs) Handles TextBox1.TextChanged

End Sub

Working With TextBoxes

Lets work with some examples to understand TextBoxes.

Drag two TextBoxes (TextBox1, TextBox2) and a Button (Button1) from the toolbox.

Code to Display some text in the TextBox

We want to display some text, say, "Welcome to TextBoxes", in TextBox1 when the Button is clicked. The code looks like this:

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e_
As System.EventArgs) Handles Button1.Click
TextBox1.Text = "Welcome to TextBoxes"
End Sub

Code to Work with PassWord Character

Set the PasswordChar property of TextBox2 to *. Setting that will make the text entered in TextBox2 to be displayed as *. We want to display what is entered in TextBox2 in TextBox1. The code for that looks like this:

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e_
As System.EventArgs) Handles Button1.Click
TextBox1.Text = TextBox2.Text
End Sub

When you run the program and enter some text in TextBox2, text will be displayed as *. When you click the Button, the text you entered in TextBox2 will be displayed as plain text in TextBox1.

Code to Validate User Input

We can make sure that a TextBox can accept only characters or numbers which can restrict accidental operations. For example, adding two numbers of the form 27+2J cannot return anything. To avoid such kind of operations we use the KeyPress event of the TextBox.

Code that allows you to enter only double digits in a TextBox looks like this:

Private Sub TextBox1_KeyPress(ByVal sender As Object,ByVal e As_
System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
If(e.KeyChar < "10" Or e.KeyChar > "100") Then
MessageBox.Show("Enter Double Digits")
End If
End Sub

Creating a TextBox in Code

Public Class Form1 Inherits System.Windows.Forms.Form
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As_
System.EventArgs) Handles MyBase.Load
Dim TextBox1 as New TextBox()
TextBox1.Text="Hello Mate"
TextBox1.Location=New Point(100,50)
TextBox1.Size=New Size(75,23)
Me.Controls.Add(TextBox1)
End Sub
End Class

***********************************************************************

Button

One of the most popular control in Visual Basic is the Button Control (previously Command Control). They are the controls which we click and release to perform some action. Buttons are used mostly for handling events in code, say, for sending data entered in the form to the database and so on. The default event of the Button is the Click event and the Button class is based on the ButtonBase class which is based on the Control class.

Button Event

The default event of the Button is the Click event. When a Button is clicked it responds with the Click Event. The Click event of Button looks like this in code:

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As_
System.EventArgs) Handles Button1.Click
'You place the code here to perform action when Button is clicked
End Sub

Working with Buttons

Well, it's time to work with Buttons. Drag a Button from the toolbox onto the Form. The default text on the Button is Button1. Click on Button1 and select it's properties by pressing F4 on the keyboard or by selecting
View->Properties Window from the main menu. That displays the Properties for Button1.

Important Properties of Button1 from Properties Window:

Appearance

Appearance section of the properties window allows us to make changes to the appearance of the Button. With the help of BackColor and Background Image properties we can set a background color and a background image to the button. We set the font color and font style for the text that appears on button with ForeColor and the Font property. We change the appearance style of the button with the FlatStyle property. We can change the text that appears on button with the Text property and with the TextAlign property we can set where on the button the text should appear from a predefined set of options.

Behavior

Notable Behavior properties of the Button are the Enabled and Visible properties. The Enabled property is set to True by default which makes the button enabled and setting it's property to False makes the button Disabled. With the Visible property we can make the Button Visible or Invisible. The default value is set to True and to make the button Invisible set it's property to False.

Layout

Layout properties are about the look of the Button. Note the Dock property here. A control can be docked to one edge of its parent container or can be docked to all edges and fill the parent container. The default value is set to none. If you want to dock the control towards the left, right, top, bottom and center you can do that by selecting from the button like image this property displays. With the Location property you can change the location of the button. With the Size property you can set the size of the button. Apart from the Dock property you can set it's size and location by moving and stretching the Button on the form itself.

Creating a Button in Code

Below is the code to create a button.

Public Class Form1 Inherits System.Windows.Forms.Form
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e_
As System.EventArgs) Handles_ MyBase.Load
Dim Button1 as New Button()
'declaring the button, Button1
Button1.Text="Creating a Button"
'setting the text to be displayed on the Button
Button1.Location=New Point(100,50)
'setting the location for the Button where it should be created
Button1.Size=New Size(75,23)
'setting the size of the Button
Me.Controls.Add(Button1)
'adding the Button that is created to the form
'the Me keyword is used to refer to the current object, in this case the Form
End Sub
End Class

********************************************************************

CheckBox

CheckBoxes are those controls which gives us an option to select, say, Yes/No or True/False. A checkbox is clicked to select and clicked again to deselect some option. When a checkbox is selected a check (a tick mark) appears indicating a selection. The CheckBox control is based on the TextBoxBase class which is based on the Control class.

Important properties of the CheckBox in the Appearance section of the properties window are:

Appearance: Default value is Normal. Set the value to Button if you want the CheckBox to be displayed as a Button.
BackgroundImage: Used to set a background image for the checkbox.
CheckAlign: Used to set the alignment for the CheckBox from a predefined list.
Checked: Default value is False, set it to True if you want the CheckBox to be displayed as checked.
CheckState: Default value is Unchecked. Set it to True if you want a check to appear. When set to Indeterminate it displays a check in gray background.
FlatStyle: Default value is Standard. Select the value from a predefined list to set the style of the checkbox.

Important property in the Behavior section of the properties window is the ThreeState property which is set to False by default. Set it to True to specify if the Checkbox can allow three check states than two.

CheckBox Event

The default event of the CheckBox is the CheckedChange event which looks like this in code:

Private Sub CheckBox1_CheckedChanged(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles CheckBox1.CheckedChanged

End Sub

Working with CheckBoxes

Lets work with an example. Drag a CheckBox (CheckBox1), TextBox (TextBox1) and a Button (Button1) from the Toolbox.

Code to display some text when the Checkbox is checked

Private Sub CheckBox1_CheckedChanged(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles CheckBox1.CheckedChanged
TextBox1.Text = "CheckBox Checked"
End Sub

Code to check a CheckBox's state

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As_
System.EventArgs) Handles Button1.Click
If CheckBox1.Checked = True Then
TextBox1.Text = "Checked"
Else
TextBox1.Text = "UnChecked"
End If
End Sub

Creating a CheckBox in Code

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As_
System.EventArgs) Handles_ MyBase.Load
Dim CheckBox1 As New CheckBox()
CheckBox1.Text = "Checkbox1"
CheckBox1.Location = New Point(100, 50)
CheckBox1.Size = New Size(95, 45)
Me.Controls.Add(CheckBox1)
End Sub

*********************************************************************

ListBox

The ListBox control displays a list of items from which we can make a selection. We can select one or more than one of the items from the list. The ListBox control is based on the ListControl class which is based on the Control class.

Notable Properties of the ListBox

In the Behavior Section

HorizontalScrollbar: Displays a horizontal scrollbar to the ListBox. Works when the ListBox has MultipleColumns.
MultiColumn: The default value is set to False. Set it to True if you want the list box to display multiple columns.
ScrollAlwaysVisible: Default value is set to False. Setting it to True will display both Vertical and Horizontal scrollbar always.
SelectionMode: Default value is set to one. Select option None if you do not any item to be selected. Select it to MultiSimple if you want multiple items to be selected. Setting it to MultiExtended allows you to select multiple items with the help of Shift, Control and arrow keys on the keyboard.
Sorted: Default value is set to False. Set it to True if you want the items displayed in the ListBox to be sorted by alphabetical order.

In the Data Section

Notable property in the Data section of the Properties window is the Items property. The Items property allows us to add the items we want to be displayed in the list box. Doing so is simple, click on the ellipses to open the String Collection Editor window and start entering what you want to be displayed in the ListBox. After entering the items click OK and doing that adds all the items to the ListBox.

ListBox Event

The default event of ListBox is the SelectedIndexChanged which looks like this in code:

Private Sub ListBox1_SelectedIndexChanged(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles ListBox1.SelectedIndexChanged

End Sub

Working with ListBoxes

Drag a TextBox and a ListBox control to the form and add some items to the ListBox with it's items property.

Referring to Items in the ListBox

Items in a ListBox are referred by index. When items are added to the ListBox they are assigned an index. The first item in the ListBox always has an index of 0 the next 1 and so on.

Code to display the index of an item

Private Sub ListBox1_SelectedIndexChanged(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles ListBox1.SelectedIndexChanged
TextBox1.Text = ListBox1.SelectedIndex
'using the selected index property of the list box to select the index
End Sub

When you run the code and select an item from the ListBox, it's index is displayed in the textbox.

Counting the number of Items in a ListBox

Add a Button to the form and place the following code in it's click event.

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e _
As System.EventArgs) Handles Button1.Click
TextBox1.Text = ListBox1.Items.Count
'counting the number of items in the ListBox with the Items.Count
End Sub

When you run the code and click the Button it will display the number of items available in the ListBox.

Code to display the item selected from ListBox in a TextBox

Private Sub ListBox1_SelectedIndexChanged(ByVal sender As System.Object,_
ByVal e As System.EventArgs) Handles ListBox1.SelectedIndexChanged
TextBox1.Text = ListBox1.SelectedItem
'using the selected item property
End Sub

When you run the code and click an item in the ListBox that item will be displayed in the TextBox.

Code to Remove items from a ListBox

You can remove all items or one particular item from the list box.

Code to remove a particular item

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e _
As System.EventArgs) Handles Button1.Click
ListBox1.Items.RemoveAt(4)
'removing an item by specifying it's index
End Sub

Code to Remove all items

Private Sub Button1_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles Button1.Click
ListBox1.Items.Clear()
'using the clear method to clear the list box
End Sub

***********************************************************************

RadioButton

RadioButtons are similar to CheckBoxes but RadioButtons are displayed as rounded instead of boxed as with a checkbox. Like CheckBoxes, RadioButtons are used to select and deselect options but they allow us to choose from mutually exclusive options. The RadioButton control is based on the ButtonBase class which is based on the Control class. A major difference between CheckBoxes and RadioButtons is, RadioButtons are mostly used together in a group.

Important properties of the RadioButton in the Appearance section of the properties window are:

Appearance: Default value is Normal. Set the value to Button if you want the RadioButton to be displayed as a Button.
BackgroundImage: Used to set a background image for the RadioButton.
CheckAlign: Used to set the alignment for the RadioButton from a predefined list.
Checked: Default value is False, set it to True if you want the RadioButton to be displayed as checked.
FlatStyle: Default value is Standard. Select the value from a predefined list to set the style of the RadioButton.

RadioButton Event

The default event of the RadioButton is the CheckedChange event which looks like this in code:

Private Sub RadioButton1_CheckedChanged(ByVal sender As System.Object,_
ByVal e As System.EventArgs) Handles RadioButton1.CheckedChanged

End Sub

Working with Examples

Drag a RadioButton (RadioButton1), TextBox (TextBox1) and a Button (Button1) from the Toolbox.

Code to display some text when the RadioButton is selected

Private Sub RadioButton1_CheckedChanged(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles RadioButton1.CheckedChanged
TextBox1.Text = "RadioButton Selected"
End Sub

Code to check a RadioButton's state

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As_
System.EventArgs) Handles Button1.Click
If RadioButton1.Checked = True Then
TextBox1.Text = "Selected"
Else
TextBox1.Text = "Not Selected"
End If
End Sub

Creating a RadioButton in Code

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As_
System.EventArgs) Handles_ MyBase.Load
Dim RadioButton1 As New RadioButton()
RadioButton1.Text = "RadioButton1"
RadioButton1.Location = New Point(120,60)
RadioButton1.Size = New Size(100, 50)
Me.Controls.Add(RadioButton1)
End Sub

************************************************************************

ComboBox

ComboBox is a combination of a TextBox and a ListBox. The ComboBox displays an editing field (TextBox) combined with a ListBox allowing us to select from the list or to enter new text. ComboBox displays data in a drop-down style format. The ComboBox class is derived from the ListBox class.

Notable properties of the ComboBox

The DropDownStyle property in the Appearance section of the properties window allows us to set the look of the ComboBox. The default value is set to DropDown which means that the ComboBox displays the Text set by it's Text property in the Textbox and displays it's items in the DropDownListBox below. Setting it to simple makes the ComboBox to be displayed with a TextBox and the list box which doesn't drop down. Setting it to DropDownList makes the ComboBox to make selection only from the drop down list and restricts you from entering any text in the textbox.

We can sort the ComboBox with it's Sorted property which is set to False by Default.

We can add items to the ComboBox with it's Items property.

ComboBox Event

The default event of ComboBox is SelectedIndexChanged which looks like this in code:

Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object,_
ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged

End Sub

Working with ComboBoxes

Drag a ComboBox and a TextBox control onto the form. To display the selection made in the ComboBox in the Textbox the code looks like this:

Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object,_
ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged
TextBox1.Text = ComboBox1.SelectedItem
'selecting the item from the ComboBox with selected item property
End Sub

Removing items from a ComboBox

You can remove all items or one particular item from the list box part of the ComboxBox. Code to remove a particular item by it's Index number looks like this:

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As_
System.EventArgs) Handles Button1.Click
ComboBox1.Items.RemoveAt(4)
'removing an item by specifying it's index
End Sub

Code to remove all items from the ComboBox

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As_
System.EventArgs) Handles Button1.Click
ComboBox1.Items.Clear()
'using the clear method to clear the list box
End Sub

************************************************************************

RichTextBox

RichTextBoxes are similar to TextBoxes but they provide some advanced features over the standard TextBox. RichTextBox allows formatting the text, say adding colors, displaying particular font types and so on. The RichTextBox, like the TextBox is based on the TextBoxBase class which is based on the Control class. These RichTextBoxes came into existence because many word processors these days allow us to save text in a rich text format. With RichTextBoxes we can also create our own word processors. We have two options when accessing text in a RichTextBox, text and rtf (rich text format). Text holds text in normal text and rtf holds text in rich text format.

RichTextBox Event

The default event of RichtextBox is the TextChanged event which looks like this in code:

Private Sub RichTextBox1_TextChanged(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles RichTextBox1.TextChanged

End Sub

Code Samples

Code for creating bold and italic text in a RichTextBox

Drag a RichTextBox (RichTextBox1) and a Button (Button1) onto the form. Enter some text in RichTextBox1, say, "We are working with RichTextBoxes". Paste the following code in the click event of Button1. The following code will search for text we mention in code and sets it to be displayed as Bold or Italic based on what text is searched for.

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e_
As System.EventArgs) Handles Button1.Click
RichTextBox1.SelectionStart = RichTextBox1.Find("are")
'using the Find method to find the text "are" and setting it's
'return property to SelectionStart which selects the text to format
Dim ifont As New Font(RichTextBox1.Font, FontStyle.Italic)
'creating a new font object to set the font style
RichTextBox1.SelectionFont = ifont
'assigning the value selected from the RichTextBox the font style
RichTextBox1.SelectionStart = RichTextBox1.Find("working")
Dim bfont As New Font(RichTextBox1.Font, FontStyle.Bold)
RichTextBox1.SelectionFont = bfont
End Sub

When you run the above code and click Button1, the text "are" is displayed in Italic and the text "working" is displayed in Bold font. The image below displays the output.

Code for Setting the Color of Text

Lets work with previous example. Code for setting the color for particular text looks like this:

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
System.EventArgs) Handles Button1.Click
RichTextBox1.SelectionStart = RichTextBox1.Find("are")
'using the Find method to find the text "are" and setting it's return
'property to SelectionStart which selects the text
RichTextBox1.SelectionColor = Color.Blue
'setting the color for the selected text with SelectionColor property
RichTextBox1.SelectionStart = RichTextBox1.Find("working")
RichTextBox1.SelectionColor = Color.Yellow
End Sub

The output when the Button is Clicked is the text "are" being displayed in Blue and the text "working" in yellow as shown in the image below.

Code for Saving Files to RTF

Drag two RichTextBoxes and two Buttons (Save, Load) onto the form. When you enter some text in RichTextBox1 and click on Save button, the text from RichTextBox1 is saved into a rtf (rich text format) file. When you click on Load button the text from the rtf file is displayed into RichTextBox2. The code for that looks like this:

Private Sub Save_Click(ByVal sender As System.Object, ByVal e As_
System.EventArgs) Handles Save.Click
RichTextBox1.SaveFile("hello.rtf")
'using SaveFile method to save text in a rich text box to hard disk
End Sub

Private Sub Load_Click(ByVal sender As System.Object, ByVal e As_
System.EventArgs) Handles Load.Click
RichTextBox2.LoadFile("hello.rtf")
'using LoadFile method to read the saved file
End Sub

********************************************************************************

TreeView

The tree view control is used to display a hierarchy of nodes (both parent, child). You can expand and collpase these nodes by clicking them. This control is similar to Windows Explorer which displays a tree view in it's left pane to list all the folders on the hard disk.

Notable Properties of TreeView

Bounds: Gets the actual bound of the tree node
Checked: Gets/Sets whether the tree node is checked
FirstNode: Gets the first child tree node
FullPath: Gets the path from the root node to the current node
ImageIndex: Gets/Sets the image list index of the image displayed for a node
Index: Gets the location of the node in the node collection
IsEditing: Gets whether the node can be edited
IsExpaned: Gets whether the node is expaned
IsSelected: Gets whether the node is selected
LastNode: Gets the last child node
NextNode: Gets the next sibling node
NextVisibleNode: Gets the next visible node
NodeFont: Gets/Sets the font for nodes
Nodes: Gets the collection of nodes in the current node
Parent: Gets the parent node of the current node
PrevNode: Gets the previous sibling node
PrevVisibleNode: Gets the previous visible node
TreeView: Gets the node's parent tree view

TreeView Event

Default event of the Tree View control is the AfterSelect event which looks like this in code:

Private Sub TreeView1_AfterSelect(ByVal sender As System.Object, ByVal e As_
System.Windows.Forms.TreeViewEventArgs) Handles TreeView1.AfterSelect

End Sub

Working with Tree Views

Drag a Tree View control on to a form and to add nodes to it select the nodes property in the properties window

To start adding nodes, you should click the Add Root button, which adds a top-level node. To add child nodes to that node, you should select that node and use the Add Child button. To set text for a node, select the node and set it's text in the textbox as shown in the image above.

Assuming you added some nodes to the tree view, drag two Labels (Label1, Label2) from the toolbox on to the form. The following code displays the node you select on Label2 and the path to that node on Label1. The code looks like this:

Public Class Form12 Inherits System.Windows.Forms.Form
#Region " Windows Form Designer generated code "

#End Region

Private Sub TreeView1_AfterSelect(ByVal sender As System.Object, ByVal e As_
System.Windows.Forms.TreeViewEventArgs) Handles TreeView1.AfterSelect
Label1.Text = "You are here->" & " " & e.Node.FullPath
'displaying the path of the selected node
Label2.Text = "Current node selected:" & " " & e.Node.Text
'displaying the selected node
End Sub

End Class

*****************************************************************************

Menus

Everyone should be familiar with Menus. Menus (File, Edit, Format etc in all windows applications) are those that allow us to make a selection when we want to perform some action with the application, for example, to format the text, open a new file, print and so on. In VB .NET MainMenu is the container for the Menu structure of the form. Menus are made of MenuItem objects that represent individual parts of a menu (like File->New, Open, Save, Save As etc). The two main classes involved in menu handling are, MainMenu and MenuItem. The MainMenu class let's us assign objects to a form's menu class and MenuItem is the class which supports the items in a menu system. Menus like File, Edit, Format etc and the items in those Menus are supported by this MenuItem class. It's this MenuItem's click event that makes these Menus work. For a MenuItem to be displayed, we need to add it to a MainMenu object.

Event of the MenuItem

The default event of the MenuItem is the Click event which looks like this in code:

Private Sub MenuItem1_Click(ByVal sender As System.Object, ByVal e As_
System.EventArgs) Handles MenuItem1.Click

End Sub

Notable properties of the MenuItem class are summarized below.

Under the Miscellaneous Section of the properties window:

Checked: Default value is set to False. Changing it to True makes a checkmark appear towards the left of the Menu.
DefaultItem: Default value is set to False. Changing it to True makes this menu item default menu item.
RadioCheck: Changing it to True makes a menu item display a radio button instead of a checkmark.
Shortcut: Enables to set a short cut key from a list of available shortcuts for the menu item.

Working with Menus

Creating Menus is simple. Drag a MainMenu component from the toolbar onto the form. When you add a MaiuMenu component to the form it appears in the component tray below the form. Windows form designer will add the MenuItem's for this by default, you need not add this. Once when you finish adding a MainMenu component to the form you will notice a "TypeHere" box towards the top-left corner of the form. To create a menu all you have to do is click on the "TypeHere" text which opens up a small textbox allowing you to enter text for the menu. You can view that in the image below. You can use the arrow keys on the keyboard to create a submenu or add other items to that menu or click on the first menu item and use the left/right arrow keys on the keyboard to create a new menu item. That's all it takes to add a menu to the form.

Working with an example

Let's work with an example to understand Menus. Drag a MainMenu and a TextBox onto the form. In the "Type Here" part, type File and under file type "New" and "Exit". Our intention here is to display "Welcome to Menus" in the TextBox when "New" is clicked and close the form when "Exit" is clicked. The Menu which we will create should look like this File->New, Exit (New and Exit below File). The code for that looks like this:

Public Class Form3 Inherits System.Windows.Forms.Form
#Region " Windows Form Designer generated code "

Private Sub MenuItem2_Click(ByVal sender As System.Object, ByVal e_
As System.EventArgs)_ Handles MenuItem2.Click
TextBox1.Text = "Welcome to Menus"
End Sub

Private Sub MenuItem3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)_ Handles MenuItem3.Click
Me.Close()
'Me refers to the current object (form)
End Sub

End Class

*********************************************************************************

Tool Tips, ErrorProvider

ToolTip

ToolTips are those small windows which display some text when the mouse is over a control giving a hint about what should be done with that control. ToolTip is not a control but a component which means that when we drag a ToolTip from the toolbox onto a form it will be displayed on the component tray. Tooltip is an Extender provider component which means that when you place an instance of a ToolTipProvider on a form, every control on that form receives a new property. This property can be viewed and set in the properties window where it appears as Tooltip on n, where n is the name of the ToolTipProvider.

To assign ToolTip's with controls we use it's SetToolTip method.

Notable property of the ToolTip is the Active property which is set to True by default and which allows the tool tip to be displayed.

Setting a ToolTip

Assume that we have a TextBox on the form and we want to display some text when your mouse is over the TextBox. Say the text that should appear is "Do not leave this blank". The code for that looks like this:

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e_
As System.EventArgs) Handles MyBase.Load
ToolTip1.SetToolTip(TextBox1, "Do not leave this blank")
End Sub

ErrorProvider Component

The ErrorProvider component provides an easy way to set validation errors. It allows us to set an error message for any control on the form when the input is not valid. When an error message is set, an icon indicating the error will appear next to the control and the error message is displayed as Tool Tip when the mouse is over the control.

Notable property of ErrorProvider in the Appearance section is the Icon property which allows us to set an icon that should be displayed. Notable property in Behavior section is the BlinkRate property which allows to set the rate in milliseconds at which the icon blinks.

Displaying an Error

Let's work with an example. Assume we have a TextBox and a Button on a form. If the TextBox on the form is left blank and if the Button is clicked, an icon will be displayed next to the TextBox and the specified text will appear in the Tool Tip box when the mouse is over the control. The code for that looks like this:

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e_
As System.EventArgs) Handles Button1.Click
If TextBox1.Text = "" Then
ErrorProvider1.SetError(TextBox1, "Cannot leave textbox blank")
Else
ErrorProvider1.SetError(TextBox1, "")
End If
End Sub

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