If the server application makes use of ActiveX resource files or ActiveX controls, these resources and controls must be installed on the thin client machine before the application can be executed. This is because there is no way to send such resources along with screen commands to the UI layer in a single network message, and if they are sent separately, the UI layer doesn't "know" anything about how to group them into a Screen Section item.
End users can usually install and register ActiveX controls and resources by downloading the controls from the control vendor's Web site and running the accompanying setup program.
For simple controls, end users can usually accomplish installation and registration by downloading or copying the ActiveX control files (at least a ".ocx" or ".dll" file) to their hard disk and executing the following command:
regsvr32 <ocx or dll name>
"regsvr32.exe" is normally located in the \windows\system directory and may not be in the end user's search path. Even if the control is already installed on the machine (for instance, if it came with other software that's been installed), the user may still need to register the control with "regsvr32.exe."