| Title | Build a TextBox control that displays a prompt message when the user hasn't typed anything in Visual Basic .NET |
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| Description | This example shows how to build a TextBox control that displays a prompt message when the user hasn't typed anything in Visual Basic .NET. |
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| Keywords | TextBox, PromptingTextBox, TextBox prompt, VB.NET, custom control |
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| Categories | Controls, VB.NET |
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The control inherits from TextBox and adds a new Prompt property.
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Private m_Prompt As String = "(Prompt)"
Public Property Prompt() As String
Get
Return m_Prompt
End Get
Set(ByVal Value As String)
m_Prompt = Value
End Set
End Property
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When the control gets focus, it determines whether it contains the prompt text> If it does, the control blanks the text so the user can type something new.
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<ToolboxBitmap(GetType(PromptingTextBox), _
"PromptingTextBoxTool.bmp")> _
Private Sub PromptingTextBox_GotFocus(ByVal sender As _
Object, ByVal e As System.EventArgs) Handles _
MyBase.GotFocus
If Me.Text = m_Prompt Then Me.Text = ""
Me.ForeColor = Color.Black
End Sub
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When the control loses focus, the control determines whether its text is blank. If the text is blank, the control displays its prompt and sets its foreground color to gray.
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Private Sub PromptingTextBox_LostFocus(ByVal sender As _
Object, ByVal e As System.EventArgs) Handles _
MyBase.LostFocus
If Me.Text.Length = 0 Then Me.Text = m_Prompt
If Me.Text = m_Prompt Then
Me.ForeColor = Color.Gray
Else
Me.ForeColor = Color.Black
End If
End Sub
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You're supposed to be able to set a TextBox's cue text by sending it the EM_SETCUEBANNER Message (see this MSDN article) but I have been unable make it work, possibly because I don't have visual styles set up properly or something. See also this Code Project article C# TextBox with Outlook 2007-style prompt. (And note that the prompting text box used on Microsoft's MSDN Web pages doesn't work very well either, at least in Firefox. It could be to do this really properly you would need to make more extensive modifications of the TextBox control.)
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