This Max for Live MIDI effect device and Max patch takes a single point on the screen (chosen via the mouse position and then pressing the '1' key on the computer keyboard). This pixel point is then mapped to pitch and velocity in terms of MIDI note event generation.
Max for Live performance VS Max performance:
This device / patch works much better as a standalone Max patch. I think that the reading of the disaply pixels via the Suckah object is interfering with some Live audio functions if the device is running as a Max for Live device as opposed to running as a standalone Max patch. You can compare the performance of both in the following two videos.
Download the Max for Live device: http://milkcrate.com.au/_other/downloads/M4L/little-scale.PixelPoint.amxd
Download the Max patch: http://milkcrate.com.au/_other/downloads/M4L/little-scale.PixelPoint.maxpat
Max for Live Device version:
Max Patch version: