https://learn.microsoft.com/fr-fr/dotnet/api/system.windows.controls.tooltipservice.tooltipclosingevent?view=netframework-4.8.1&viewFallbackFrom=windowsdesktop-10.0
ToolTipService.ToolTipClosingEvent Field (System.Windows.Controls) | Microsoft Learn
Identifies the ToolTipClosing event that is exposed by objects that use the ToolTipService service to display tooltips.
field systemwindows controlsmicrosoftlearn