cg: check if selection change is allowed BEFORE changing the actual selection (to avoid writing into a wrong spec). allow to paste into a non-container (search for a container)

.listOfSTfiles
.dependencies
Makefile
*.exp
*.obj
*.dll
*.lib
*.ilk
*.pdb
*.sbr
*.pch
*.c
*.sc
so_locations
classList.stc
objbc
make0000.@@@
MAKE0000.@@@