Status: Added for next update.
When you add a terrain piece you have to go to the Inspector menu and click on the very non-descriptive "..."-button to change the terrain piece into another one.
I propose to open the "Pick Terrain menu" automatically when a new terrain piece is added to the level. Of course this should not happen when just copying an already existing terrain piece.
The same arguments apply as well for objects.
I've mentioned the not-very-pleasant to use terrain/object selection system in the past. Not only that but the menu itself is annoying because it's very small [cannot be resized] and you have to scroll through it to look for whatever, and the sample pictures are small.
I'd rather have something like Lix or the chips challenge editor where you just press a button or hotkey and it brings up a grid-like menu showing all or most of the pieces. Then select one and it's added. Having a default [always the first piece in the list, which more often than not is not the piece you want] piece always added FIRST, and then having to change it is slightly annoying.
And a separate button [maybe...] to specifically just change an already existing piece. Being able to change an already existing piece is nice, but since this was a feature totally new to me, [no other editor for a game, or just about anything that I'm aware of has a function like this] it took a little getting used to in the beginning. It is useful to have, and I'm not saying we should get rid of it, but I don't use it nearly as often as I'd just like to add a new piece into the level.
Agreed. Placing a new terrain piece is the most frequent subtask of designing a level, and needs to be as easy as possible.
Implemented for next update. In case some people prefer the classic behaviour, there's an option to use it instead (new behaviour is the default).
(And yes, I made this change apply to objects as well as to terrain.)