Control.HelpRequested Event
Occurs when the user requests help for a control.
[Visual Basic] Public Event HelpRequested As HelpEventHandler [C#] public event HelpEventHandler HelpRequested; [C++] public: __event HelpEventHandler* HelpRequested;
[JScript] In JScript, you can handle the events defined by a class, but you cannot define your own.
Event Data
The event handler receives an argument of type HelpEventArgs containing data related to this event. The following HelpEventArgs properties provide information specific to this event.
| Property | Description |
|---|---|
| Handled | Gets or sets a value indicating whether the help event was handled. |
| MousePos | Gets the screen coordinates of the mouse pointer. |
Remarks
The HelpRequested event is commonly raised when the user presses the F1 key or an associated context-sensitive help button is clicked.
For more information about handling events, see Consuming Events.
Example
[Visual Basic, C#, C++] The following example demonstrates handling the HelpRequested event to display custom Help content on a form containing four address fields. The HelpRequested event is raised either by pressing the F1 key with the focus in an address field, or by the using the context-sensitive Help button and clicking the Help cursor on an address field. The Handled property is set to true to indicate that the HelpRequested event is handled. The example also demonstrates storing the Help text in the Control.Tag property.
[Visual Basic] Imports System Imports System.Drawing Imports System.Windows.Forms Public Class Form1 Inherits System.Windows.Forms.Form Private WithEvents addressTextBox As System.Windows.Forms.TextBox Private WithEvents label2 As System.Windows.Forms.Label Private WithEvents cityTextBox As System.Windows.Forms.TextBox Private WithEvents label3 As System.Windows.Forms.Label Private WithEvents stateTextBox As System.Windows.Forms.TextBox Private WithEvents zipTextBox As System.Windows.Forms.TextBox Private WithEvents helpLabel As System.Windows.Forms.Label <STAThread()> _ Shared Sub Main() Application.Run(New Form1) End Sub 'Main Public Sub New() Me.addressTextBox = New System.Windows.Forms.TextBox Me.helpLabel = New System.Windows.Forms.Label Me.label2 = New System.Windows.Forms.Label Me.cityTextBox = New System.Windows.Forms.TextBox Me.label3 = New System.Windows.Forms.Label Me.stateTextBox = New System.Windows.Forms.TextBox Me.zipTextBox = New System.Windows.Forms.TextBox ' Help Label Me.helpLabel.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D Me.helpLabel.Location = New System.Drawing.Point(8, 80) Me.helpLabel.Size = New System.Drawing.Size(272, 72) Me.helpLabel.Text = "Click on any control to give it focus, and then " & _ "press F1 to display help for that" + " control. Alternately, you can " & _ "click the help button at the top of the dialog and then click on a control." ' Address Label Me.label2.Location = New System.Drawing.Point(16, 8) Me.label2.Size = New System.Drawing.Size(100, 16) Me.label2.Text = "Address:" ' Comma Label Me.label3.Location = New System.Drawing.Point(136, 56) Me.label3.Size = New System.Drawing.Size(16, 16) Me.label3.Text = "," ' Address TextBox Me.addressTextBox.Location = New System.Drawing.Point(16, 24) Me.addressTextBox.Size = New System.Drawing.Size(264, 20) Me.addressTextBox.TabIndex = 0 Me.addressTextBox.Tag = "Enter the stree address in this text box." Me.addressTextBox.Text = "" ' City TextBox Me.cityTextBox.Location = New System.Drawing.Point(16, 48) Me.cityTextBox.Size = New System.Drawing.Size(120, 20) Me.cityTextBox.TabIndex = 3 Me.cityTextBox.Tag = "Enter the city here." Me.cityTextBox.Text = "" ' State TextBox Me.stateTextBox.Location = New System.Drawing.Point(152, 48) Me.stateTextBox.MaxLength = 2 Me.stateTextBox.Size = New System.Drawing.Size(32, 20) Me.stateTextBox.TabIndex = 5 Me.stateTextBox.Tag = "Enter the state in this text box." Me.stateTextBox.Text = "" ' Zip TextBox Me.zipTextBox.Location = New System.Drawing.Point(192, 48) Me.zipTextBox.Size = New System.Drawing.Size(88, 20) Me.zipTextBox.TabIndex = 6 Me.zipTextBox.Tag = "Enter the zip code here." Me.zipTextBox.Text = "" ' Set up how the form should be displayed and add the controls to the form. Me.ClientSize = New System.Drawing.Size(292, 160) Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.zipTextBox, _ Me.stateTextBox, Me.label3, Me.cityTextBox, _ Me.label2, Me.helpLabel, Me.addressTextBox}) Me.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedDialog Me.HelpButton = True Me.MaximizeBox = False Me.MinimizeBox = False Me.Text = "Help Event Demonstration" End Sub 'New Private Sub textBox_HelpRequested(ByVal sender As Object, ByVal hlpevent As System.Windows.Forms.HelpEventArgs) Handles addressTextBox.HelpRequested, cityTextBox.HelpRequested, stateTextBox.HelpRequested, zipTextBox.HelpRequested ' This event is raised when the F1 key is pressed or the ' Help cursor is clicked on any of the address fields. ' The Help text for the field is in the control's ' Tag property. It is retrieved and displayed in the label. Dim requestingControl As Control = CType(sender, Control) helpLabel.Text = CStr(requestingControl.Tag) hlpevent.Handled = True End Sub 'textBox_HelpRequested End Class 'Form1 [C#] using System; using System.Drawing; using System.Windows.Forms; public class Form1 : System.Windows.Forms.Form { private System.Windows.Forms.TextBox addressTextBox; private System.Windows.Forms.Label label2; private System.Windows.Forms.TextBox cityTextBox; private System.Windows.Forms.Label label3; private System.Windows.Forms.TextBox stateTextBox; private System.Windows.Forms.TextBox zipTextBox; private System.Windows.Forms.Label helpLabel; [STAThread] static void Main() { Application.Run(new Form1()); } public Form1() { this.addressTextBox = new System.Windows.Forms.TextBox(); this.helpLabel = new System.Windows.Forms.Label(); this.label2 = new System.Windows.Forms.Label(); this.cityTextBox = new System.Windows.Forms.TextBox(); this.label3 = new System.Windows.Forms.Label(); this.stateTextBox = new System.Windows.Forms.TextBox(); this.zipTextBox = new System.Windows.Forms.TextBox(); // Help Label this.helpLabel.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D; this.helpLabel.Location = new System.Drawing.Point(8, 80); this.helpLabel.Size = new System.Drawing.Size(272, 72); this.helpLabel.Text = "Click on any control to give it focus, and then " + "press F1 to display help for that control. Alternately, you can " + "click the help button at the top of the dialog and then click on a control."; // Address Label this.label2.Location = new System.Drawing.Point(16, 8); this.label2.Size = new System.Drawing.Size(100, 16); this.label2.Text = "Address:"; // Comma Label this.label3.Location = new System.Drawing.Point(136, 56); this.label3.Size = new System.Drawing.Size(16, 16); this.label3.Text = ","; // Address TextBox this.addressTextBox.Location = new System.Drawing.Point(16, 24); this.addressTextBox.Size = new System.Drawing.Size(264, 20); this.addressTextBox.TabIndex = 0; this.addressTextBox.Tag = "Enter the street address in this text box."; this.addressTextBox.Text = ""; this.addressTextBox.HelpRequested += new System.Windows.Forms.HelpEventHandler(this.textBox_HelpRequested); // City TextBox this.cityTextBox.Location = new System.Drawing.Point(16, 48); this.cityTextBox.Size = new System.Drawing.Size(120, 20); this.cityTextBox.TabIndex = 3; this.cityTextBox.Tag = "Enter the city here."; this.cityTextBox.Text = ""; this.cityTextBox.HelpRequested += new System.Windows.Forms.HelpEventHandler(this.textBox_HelpRequested); // State TextBox this.stateTextBox.Location = new System.Drawing.Point(152, 48); this.stateTextBox.MaxLength = 2; this.stateTextBox.Size = new System.Drawing.Size(32, 20); this.stateTextBox.TabIndex = 5; this.stateTextBox.Tag = "Enter the state in this text box."; this.stateTextBox.Text = ""; this.stateTextBox.HelpRequested += new System.Windows.Forms.HelpEventHandler(this.textBox_HelpRequested); // Zip TextBox this.zipTextBox.Location = new System.Drawing.Point(192, 48); this.zipTextBox.Name = "zipTextBox"; this.zipTextBox.Size = new System.Drawing.Size(88, 20); this.zipTextBox.TabIndex = 6; this.zipTextBox.Tag = "Enter the zip code here."; this.zipTextBox.Text = ""; this.zipTextBox.HelpRequested += new System.Windows.Forms.HelpEventHandler(this.textBox_HelpRequested); // Set up how the form should be displayed and add the controls to the form. this.ClientSize = new System.Drawing.Size(292, 160); this.Controls.AddRange(new System.Windows.Forms.Control[] { this.zipTextBox, this.stateTextBox, this.label3, this.cityTextBox, this.label2, this.helpLabel, this.addressTextBox}); this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedDialog; this.HelpButton = true; this.MaximizeBox = false; this.MinimizeBox = false; this.Text = "Help Event Demonstration"; } private void textBox_HelpRequested(object sender, System.Windows.Forms.HelpEventArgs hlpevent) { // This event is raised when the F1 key is pressed or the // Help cursor is clicked on any of the address fields. // The Help text for the field is in the control's // Tag property. It is retrieved and displayed in the label. Control requestingControl = (Control)sender; helpLabel.Text = (string)requestingControl.Tag; hlpevent.Handled = true; } } [C++] #using <mscorlib.dll> #using <System.dll> #using <System.Windows.Forms.dll> #using <System.Drawing.dll> using namespace System; using namespace System::Drawing; using namespace System::Windows::Forms; public __gc class Form1 : public System::Windows::Forms::Form { private: System::Windows::Forms::TextBox* addressTextBox; System::Windows::Forms::Label* label2; System::Windows::Forms::TextBox* cityTextBox; System::Windows::Forms::Label* label3; System::Windows::Forms::TextBox* stateTextBox; System::Windows::Forms::TextBox* zipTextBox; System::Windows::Forms::Label* helpLabel; public: Form1() { this->addressTextBox = new System::Windows::Forms::TextBox(); this->helpLabel = new System::Windows::Forms::Label(); this->label2 = new System::Windows::Forms::Label(); this->cityTextBox = new System::Windows::Forms::TextBox(); this->label3 = new System::Windows::Forms::Label(); this->stateTextBox = new System::Windows::Forms::TextBox(); this->zipTextBox = new System::Windows::Forms::TextBox(); // Help Label this->helpLabel->BorderStyle = System::Windows::Forms::BorderStyle::Fixed3D; this->helpLabel->Location = System::Drawing::Point(8, 80); this->helpLabel->Size = System::Drawing::Size(272, 72); this->helpLabel->Text = S"Click on any control to give it focus, and then press F1 to display help for that control. Alternately, you can click the help button at the top of the dialog and then click on a control."; // Address Label this->label2->Location = System::Drawing::Point(16, 8); this->label2->Size = System::Drawing::Size(100, 16); this->label2->Text = S"Address:"; // Comma Label this->label3->Location = System::Drawing::Point(136, 56); this->label3->Size = System::Drawing::Size(16, 16); this->label3->Text = S", "; // Address TextBox this->addressTextBox->Location = System::Drawing::Point(16, 24); this->addressTextBox->Size = System::Drawing::Size(264, 20); this->addressTextBox->TabIndex = 0; this->addressTextBox->Tag = S"Enter the street address in this text box."; this->addressTextBox->Text = S""; this->addressTextBox->HelpRequested += new System::Windows::Forms::HelpEventHandler(this, &Form1::textBox_HelpRequested); // City TextBox this->cityTextBox->Location = System::Drawing::Point(16, 48); this->cityTextBox->Size = System::Drawing::Size(120, 20); this->cityTextBox->TabIndex = 3; this->cityTextBox->Tag = S"Enter the city here."; this->cityTextBox->Text = S""; this->cityTextBox->HelpRequested += new System::Windows::Forms::HelpEventHandler(this, &Form1::textBox_HelpRequested); // State TextBox this->stateTextBox->Location = System::Drawing::Point(152, 48); this->stateTextBox->MaxLength = 2; this->stateTextBox->Size = System::Drawing::Size(32, 20); this->stateTextBox->TabIndex = 5; this->stateTextBox->Tag = S"Enter the state in this text box."; this->stateTextBox->Text = S""; this->stateTextBox->HelpRequested += new System::Windows::Forms::HelpEventHandler(this, &Form1::textBox_HelpRequested); // Zip TextBox this->zipTextBox->Location = System::Drawing::Point(192, 48); this->zipTextBox->Name = S"zipTextBox"; this->zipTextBox->Size = System::Drawing::Size(88, 20); this->zipTextBox->TabIndex = 6; this->zipTextBox->Tag = S"Enter the zip code here."; this->zipTextBox->Text = S""; this->zipTextBox->HelpRequested += new System::Windows::Forms::HelpEventHandler(this, &Form1::textBox_HelpRequested); // Set up how the form should be displayed and add the controls to the form. this->ClientSize = System::Drawing::Size(292, 160); System::Windows::Forms::Control* temp0 [] = {this->zipTextBox, this->stateTextBox, this->label3, this->cityTextBox, this->label2, this->helpLabel, this->addressTextBox}; this->Controls->AddRange(temp0); this->FormBorderStyle = System::Windows::Forms::FormBorderStyle::FixedDialog; this->HelpButton = true; this->MaximizeBox = false; this->MinimizeBox = false; this->Text = S"Help Event Demonstration"; } private: void textBox_HelpRequested(Object* sender, System::Windows::Forms::HelpEventArgs* hlpevent) { // This event is raised when the F1 key is pressed or the // Help cursor is clicked on any of the address fields. // The Help text for the field is in the control's // Tag property. It is retrieved and displayed in the label. Control* requestingControl = dynamic_cast<Control*>(sender); helpLabel->Text = dynamic_cast<String*>(requestingControl->Tag); hlpevent->Handled = true; } }; [STAThread] int main() { Application::Run(new Form1()); }
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Requirements
Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family
See Also
Control Class | Control Members | System.Windows.Forms Namespace | OnHelpRequested | HelpProvider | Help