Couple of requests:
"Do not change textures" checkbox under Edit. Sometimes I want to change a block, but want to leave the textures alone.
Some way to copy a block from Info into Edit, so that I don't have to remember the rotations, textures, etc. Ideally a right click on the block when in Info Tab, and an option to "Copy to Edit", then when I go to Edit, the block is there with all of the features. It would make changing densities so much easier.
(F)ile,(S)ave menu!
Tab going to the next field (I can understand not doing this yet if you're planning on more buttons)
Remembering the directory I loaded and/or saved the last file from/into.
A button to "Set All Faces" in the texture section, so that I can select a texture and have it set all faces, instead of having to do them one by one.
A way to search for Textures.