The latest version of GP, v064, is at http://tinlizzie.org/gp.
This version includes graphics and project loading optimizations that were motivated by the need for better performance in mobile browsers but which benefit all platforms. It also includes some memory optimizations and better management of garbage collection. GP is less likely to run out of memory and more likely to handle running out of memory gracefully (i.e. by presenting an error message or debugger rather than crashing). Several bugs were fixed including a bug that gave an error when trying to save a project containing an empty "if" block.
New features include:
• A built-in "block finder" widget
• The ability to export pictures of individual scripts or the contents of the scripting pane as a .PNG file
Note for Mac OS X Sierra users:
Sierra has added additional security features. To run GP, you must first unzip it, then drag the GP.app file into the Applications folder. Then, select "Open" from the right-click menu. This should allow you to run it after warning you that its not from the Apple App store. I believe that once that's been done, you can drag GP.app back into the GP folder and put the folder anywhere you like. I have not yet upgraded to Sierra, so I can't test this myself. Let me know if you have problems. Many thanks to Mark Guzdial, who helped me debug this puzzling problem.