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.
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