Windows Forms Programming in C#

Custom Designers

So far, you have seen how properties are exposed to the developer at design time, and you've seen some of the key infrastructure provided by .NET to improve the property-editing experience, culminating in UITypeEditor. Although the focus has been on properties, they aren't the only aspect of a control that operates differently in design-time mode compared with run-time mode. In some situations, a control's UI might render differently between these modes.

For example, the Splitter control displays a dashed border when its BorderStyle is set to BorderStyle.None. This design makes it easier for developers to find this control on the form's design surface in the absence of a visible border, as illustrated in Figure 9.32.

Figure 9.32. ...