A control appears flat until the mouse pointer moves over it, at which point it appears three-dimensional.
Syntax
FlatStyle Popup
Requirements
Namespace: System.Windows.Forms
Assembly: System.Windows.Forms (in System.Windows.Forms.dll)
Assembly Versions: 1.0.5000.0, 2.0.0.0
Assembly: System.Windows.Forms (in System.Windows.Forms.dll)
Assembly Versions: 1.0.5000.0, 2.0.0.0