In the meantime you can get around this problem by forcing DPlot to use its own clipping routines rather than a Windows API function.
- Shut down DPlot if it is running.
- Start Notepad. Open the file %APPDATA%\DPlot\dplot.ini
- Scroll to the end of that file and add these 2 lines:
[Debugging]
UseDPLOTClipping=1 - Save the file and exit Notepad.