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TabControl.Selecting Event

Occurs before a tab is selected, enabling a handler to cancel the tab change.

Namespace:  System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)

public event TabControlCancelEventHandler Selecting

When the current tab changes in a TabControl, the following events occur in the following order.

These events let you perform tasks such as canceling a tab change if a TabPage is in an invalid state or updating the state of a newly displayed TabPage.

The current tab changes when the user clicks a tab, when you call the DeselectTab or SelectTab method, or when you change the value of the SelectedIndex or SelectedTab property.

The following code example demonstrates the use of this member. In the example, an event handler reports on the occurrence of the Selecting event. This report helps you to learn when the event occurs and can assist you in debugging. To report on multiple events or on events that occur frequently, consider replacing MessageBox.Show with Console.WriteLine or appending the message to a multiline TextBox.

To run the example code, paste it into a project that contains an instance of type TabControl named TabControl1. Then ensure that the event handler is associated with the Selecting event.

private void TabControl1_Selecting(Object sender, TabControlCancelEventArgs e) {

System.Text.StringBuilder messageBoxCS = new System.Text.StringBuilder();
messageBoxCS.AppendFormat("{0} = {1}", "TabPage", e.TabPage );
messageBoxCS.AppendLine();
messageBoxCS.AppendFormat("{0} = {1}", "TabPageIndex", e.TabPageIndex );
messageBoxCS.AppendLine();
messageBoxCS.AppendFormat("{0} = {1}", "Action", e.Action );
messageBoxCS.AppendLine();
messageBoxCS.AppendFormat("{0} = {1}", "Cancel", e.Cancel );
messageBoxCS.AppendLine();
MessageBox.Show(messageBoxCS.ToString(), "Selecting Event" );
}

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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