https://learn.microsoft.com/en-us/dotnet/api/system.windows.interop.hwndsourceparameters.hasassignedsize?view=netframework-4.8.1&viewFallbackFrom=windowsdesktop-10.0
HwndSourceParameters.HasAssignedSize Property (System.Windows.Interop) | Microsoft Learn
Gets a value that indicates whether a size was assigned.
property systemwindowsinteropmicrosoftlearn