OK Roman and Christof, after some reflection I think now you are right, to assume different behaviors for different contexts!
- in a symbol atom, a space would be implicitly part of the symbol (if this is accepted);
- in a list atom, space is the delimiter, so if you want an actual space it has to be escaped;
- in a float atom, no space at all is allowed... (BTW wouldn't it be a nice addition to filter the keyboard input to only numeric characters in the "number" context?...)
- [message boxes( and [objects] behave like lists.