Many ActiveX controls define a built-in dialog for making property settings at design-time. This dialog is available in the visual designer by selecting "ActiveX Properties…" from the control's context menu.
The dialog that is displayed belongs to the ActiveX control and will vary for each different type of control. The example below shows the Calendar control's design-time properties dialog.
When you set ActiveX properties in the Studio the states of each property you set is serialized into a base64 format and embedded in the source code within a Embed_ActiveX_Resource / End_Embed_ActiveX_Resource section in the object declaration. When you compile an application, the ActiveX controls' property values, are compiled into the application .exe.
Using COM Components in the Studio