Clipboard.RawDataAvailable
From Xojo Documentation
Method
Returns True if the Clipboard contains data.
Notes
The DataType parameter supports both the older MacType and newer UTIs. If the DataType parameter is exactly 4 bytes then it is treated as a MacType for backwards compatibility. Otherwise it is treated as a UTI.
On Windows you can use the a special DataType called "HTML Format" to add or fetch HTML data from the clipboard[1].
Sample Code
The following code checks the RawDataAvailable flag prior to reading the contents of the Clipboard.