Didn't pay close enough attention to see if Growthcraft items were appearing on every single tab page in creative; however, there's usually a section of Growthcraft items either before or after another mods displayed items in a given tab. There's also a crowbar (or sword, I forget which) that displays in the delete item slot in the players inventory in creative. It seems that it's simply an overlay rather than an actual item you can click on with the mouse.

Good work by the way. Can't wait to see more development on this awesome mod. Many thanks.

In the newest version 4.0.2 this one should be fixed.

Many thanks.