The data receiver (target) duties

To receive (paste in usual terminology) data from the clipboard, you should create a wxDataObject derived class which supports the data formats you need and pass it as argument to wxClipboard::GetData. If it returns false, no data in (any of) the supported format(s) is available. If it returns true, the data has been successfully transferred to wxDataObject.

For drag and drop case, the wxDropTarget::OnData virtual function will be called when a data object is dropped, from which the data itself may be requested by calling wxDropTarget::GetData method which fills the data object.