Unsupported system functions

Table 8-2 lists categories of system functions that are not supported or are deferred until a future release:

**Table 8-2: Unsupported system functions by category**
Category	Functions
Clipboard functions	Clipboard, also any object function that uses the clipboard, such as Copy, Paste, Clear, and so on
DDE functions	CloseChannel, ExecRemote, GetCommandDDE, GetCommandDDEOrigin, GetDataDDE, GetDataDDEOrigin, GetRemote, OpenChannel, RespondRemote, SetDataDDE, SetRemote, StartHotLink, StartServerDDE, StopHotLink, StopServerDDE
Debugging functions	DebugBreak
Garbage collection functions	GarbageCollect, GarbageCollectGetTimeLimit, GarbageCollectSetTimeLimit
Help functions	ShowHelp, ShowPopupHelp
Input method functions	IMEGetCompositionText, IMEGetMode, IMESetMode
Mail functions	MailAddress, MailDeleteMessage, MailGetMessages, MailHandle, MailLogoff, MailLogon, MailReadMessage, MailRecipientDetails, MailResolveRecipient, MailSaveMessage
Messaging functions	Post, Send
Miscellaneous functions	DoScript, DraggedObject, Handle, Run, Restart
Print functions	PrintDataWindow, PrintScreen, PrintSend, PrintSetPrinter, PrintSetup, PrintSetupPrinter
Profiling and tracing functions	TraceBegin, TraceClose, TraceDisableActivity, TraceDump, TraceEnableActivity, TraceEnd, TraceError, TraceOpen, TraceUser

Partially supported system function

IsNull function The IsNull function is supported for simple datatypes only. It is not very useful for structure and class objects, since in .NET targets, uninitialized variables always return true for an IsNull call even when they are not explicitly set to null. However, you can use IsValid to test for valid instances of these object types. You can also use IsNull for class objects after they have been created.

Timer function The concept of “current window” does not exist in Web Forms applications. Therefore, you must use the optional PowerScript syntax with the window name parameter and the name of an active window as the parameter value. The Timer function fails when the active window does not exist.

Yield function Due to the thread-model design of Web Forms applications, you cannot use the Yield function and the Selected event of a menu object concurrently. Doing this causes a JavaScript error.

Registry functions System registry functions can read and write registry entries, keys, and values on the server side, but do not perform these operations on the server computer’s registry in the same way as they do on a client computer’s registry in a standard PowerBuilder application.

For more information on system registry functions, see “Using the registry functions”.