The STrackSelection service allows extended interaction between the host's property browser and an ActiveX designer. A browser can change the current selection, show or hide the property browser, and allow selections of groups of subobjects in the ActiveX designer.
STrackSelection defines two interfaces, ISelectionContainer and ITrackSelection, as listed in the following table:
| Interface | Method | Description |
| ISelectionContainer | CountObjects | Returns the number of selected or selectable objects. |
| GetObjects | Returns the selected or selectable objects. | |
| SelectObjects | Selects a single object. | |
| ITrackSelection | OnSelectChange | Passes a pointer to ISelectionContainer. |
The ActiveX designer implements the ISelectionContainer interface and calls OnSelectChange to pass the host a pointer to this interface. After it has the pointer, the host can call the methods in ISelectionContainer in response to user selections.
The service identifier (SID) for this service is SID_STrackSelection.