C# WinForms Form Event Order

Sometimes it’s important to understand the order of events that occur when a WinForms Form is opened, closed, shown or hidden.  There are also a few “gotchas” that are important to know.

Form Open

Following is the order of events when a Form is opened.  Note that the Form’s Visible and IsDisposed property values are listed when each event is raised:

Event	Visible	IsDisposed
call form.Show() method	false	false
Control.HandleCreated	false	false
Control.BindingContextChanged	true	false
Form.Load	true	false
Control.VisibleChanged	true	false
Control.GotFocus	true	false
Form.Activated	true	false
Form.Shown	true	false

Things to note:

• The Form becomes Visible starting with the BindingContextChanged event.
• The GotFocus event will typically not fire if the form contains controls, as one of these controls will likely get focus when the form is shown.
   

Form Close

This is the order of events when a Form is closed:

Event	Visible	IsDisposed
call form.Close() method	true	false
Form.Closing	true	false
Form.FormClosing	true	false
Form.Closed	true	false
Form.FormClosed	true	false
Form.Deactivate	true	false
Control.LostFocus	true	false
Control.HandleDestroyed	true	false
Component.Disposed	false	false
after Disposed event	false	true

Things to note:

• The Form is no longer Visible starting with the Disposed event.
• This means that the Form is still Visible during the FormClosed event!
• The Closing and Closed events were marked obsolete in .NET 2.0.  You should use the FormClosing and FormClosed events instead.
• The Closing and Closed events are not raised when the Application.Exit method is called to exit your application.  Which is just another reason why you should avoid using these events.
• You can prevent the Form from closing during the Closing event.
• The Deactivate and LostFocus events are raised only if the Form had focus when it was closed.
• The Form is not marked as IsDisposed until after the Disposed event.
   

Form Hide

This is the order of events when a Form is hidden:

Event	Visible
set form.Visible = false	true
Form.Deactivate	true
Control.LostFocus	true
Control.VisibleChanged	false

Things to note:

• The Form is no longer Visible starting with the VisibleChanged event.
• The Deactivate and LostFocus events are raised only if the Form had focus when it was hidden.
   

Form Show

This is the order of events when a hidden Form is shown:

Event	Visible
set form.Visible = true	false
Control.VisibleChanged	true
Control.GotFocus	true
Form.Activated	true

Things to note:

• The Form becomes Visible starting with the VisibleChanged event.
• The GotFocus event will typically not fire if the form contains controls, as one of these controls will likely get focus when the form is shown. 
• When hiding or closing a form, Deactivate is raised, then LostFocus.  But when showing a form, the order is reversed: GotFocus is raised, then Activated.  These events are also raised when a form loses and gains focus.