[Toolboxbitmap (typeof (myopaquelayer)] [category ("myopaquelayer"), description ("

These two attributes are used for custom controls, which are generally placed before the class of custom controls. [Toolboxbitmap (typeof (myopaquelayer)] specifies the icon displayed in the toolbar when you add a custom control to the toolbar. The correct syntax is [toolboxbitmap (typeof (xxxxcontrol), "xxx.bmp")] Where xxxxcontrol is your custom control and "xxx.bmp" is the name of the icon you want to use. For specific settings, search for toolboxbitmap in Baidu. You should be able to find more detailed answers. [Category ("myopaquelayer"), description ("whether transparent, true by default")] This is simpler. It is generally used to describe the properties of your custom control ). Category is used to indicate the category of the attribute. description is the meaning of the attribute. After setting these settings, you can drag a custom control to the design interface and view the Properties window.