Form.ResizeBegin Event


Occurs when a form enters resizing mode.

 event EventHandler ^ ResizeBegin;
public event EventHandler ResizeBegin;
public event EventHandler? ResizeBegin;
member this.ResizeBegin : EventHandler 
Public Custom Event ResizeBegin As EventHandler 

Event Type



The following example demonstrates the use of this member. In the example, an event handler reports on the occurrence of the ResizeBegin 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 Form named Form1. Then ensure that the event handler is associated with the ResizeBegin event.

private void Form1_ResizeBegin(Object sender, EventArgs e) {

   MessageBox.Show("You are in the Form.ResizeBegin event.");
Private Sub Form1_ResizeBegin(sender as Object, e as EventArgs) _ 
     Handles Form1.ResizeBegin

   MessageBox.Show("You are in the Form.ResizeBegin event.")

End Sub


The ResizeBegin event is raised when the user begins to resize a form, typically by clicking and dragging one of the borders or the sizing grip located on the lower-right corner of the form. This action puts the form into a modal sizing loop until the resize operation is completed. Typically, the following set of events occurs during a resize operation:

  1. A single ResizeBegin event occurs as the form enters resizing mode.

  2. Zero or more pairs of Resize and SizeChanged events occur as the form's Size is modified.

  3. A single ResizeEnd event occurs as the form exits resizing mode.


Just clicking without dragging on a border or resizing grip will generate the ResizeBegin and ResizeEnd events without any intermediate Resize and SizeChanged event pairs.

The ResizeBegin and ResizeEnd pair of events is also raised when the user moves the form, typically by clicking and dragging on the caption bar. These events are not generated by programmatic manipulation of the form, for example by changing the Size or Location properties.

For more information about handling events, see Handling and Raising Events.

Applies to

See also