SPContext.IsRemoteAuthoringTime property

Gets a value that represents whether the current request renders for design time.

Namespace:  Microsoft.SharePoint
Assembly:  Microsoft.SharePoint (in Microsoft.SharePoint.dll)

public bool IsRemoteAuthoringTime { get; }

Property value

Type: System.Boolean
Returns a Boolean value of true if the Current request is rendering for design time.

When the web request is operating in a design-time configuration, some Web server controls need to be serialized and deserialized differently.