I feel like a bit of a duffer about this as I know that I have had Processing working before, however...
I opened Processing today after a long time since last using it and I cannot type anything into the Text Editor window.
My Macbook is making a default 'cannot type here' blip-noise when I try and type into the Text Editor and the BG of the text editor window is blue not white as I would expect.
I can create new sketches but it is still the same when I try and type. I have restarted, uninstalled and re-installed Processing. I have also deleted the preferences file from my library and restarted Processing.
I can open code examples (white BG shows then in the Text Editor) but I cannot edit the examples or even press return in the Text Editor window without my Mac making the 'can't type here' noise and refusing to allow me to add code.