Options for object creation are greyed out I am trying to model a tree. I turned on the Add a sapling add-on in user preferences, however once I want to begin editing the settings, they come up but is grey and doesn't let me click on it.



I have also attached my blend file here: http://www.pasteall.org/blend/32199
You have to enable: Global Undo
For 2.8x and 2.9.
Edit &gt; User preferences &gt; System &gt; Memory &amp; Limits: Global Undo

For 2.79
You can do it in User Preferences (Ctrl+ Alt U), in &quot;Editing&quot; Tab.