Control的默认属性

Question

When I add a control to a form through the designer, not all properties of the control appear in the designer code. For example, when I add a ListBox the UseWaitCursor property does not appear in the designer code unless it is set to True . When I change it to False it disappears from the designer code, which makes me think that the properties somehow have defaults and don't appear in the designer code if left at default.

Can someone please help me understand how the designer works and where all this is tracked. The reason I ask is I am currently writing a class that extends a third party ActiveX control which I plan to initialize dynamically at run time. I was going through the designer code (when the third party control is added through the designer) and a lot of its properties do not appear there.

Answer 1

This is done with the [DefaultValue] attribute. The Control.UseWaitCursor property looks similar to this:

[DefaultValue(false)]
public bool UseWaitCursor
{
   // etc..
}

So if you leave the value at False in the Properties window then the designer knows that it should not display the value in Bold and that it is not necessary to put the property assignment in the InitializeComponent() method since the default is already good. An ActiveX control will certainly have a lot of properties set at its default value as well.