What steps will reproduce the problem? 1. Type something 2. Select and replace with something 3. try to undo last operation

What is the expected output? What do you see instead?

What version of the product are you using? On what operating system?

Please provide any additional information below.

UNDO dont work :(

Very important issue ! Ii've just delete "a group" in place of a "snippet" and discovered that undo command doesn't exists (mac OX.10.5.3 version)....just lost 30 minutes of work...:-/ But Snippely stay very usefull ;-)

Agreed as well. There needs to be an undo feature in an environment that easily copies, replaces, and pastes code.