Which of the following is true?
-
User controls are displayed correctly in the Visual Studio .NET Designer
-
Custom controls are displayed correctly in VS.Net Designer
-
User and Custom controls are displayed correctly in the Visual Studio .NET Designer.
Custom controls render correctly in the Visual Studio .NET Designer, while user controls do not always display properly during design-time. This is because user controls (.ascx files) have dependencies and runtime context that the designer cannot fully replicate, whereas custom controls are compiled assemblies designed to work at design-time. This is a known limitation of user controls.
Historically, the Visual Studio .NET WinForms/WebForms designer could render compiled custom controls correctly because it could instantiate and draw them directly, but user controls (.ascx, composed of markup) often failed to render properly in the designer surface due to how the designer handled their child controls and code-behind. That's why "custom controls display correctly" is the accurate statement, while claims that user controls (or both) render correctly are not.