strage emerge world behaviour. maybe a bug?

[GilGalaad]

i have a question about emerge and dependancies, that come out while emerging -up world.
there's a strage behaviour that i think should be fixed.
while installing my system, i emerged cdrtools manually, and then xcdroast, so BOTH packages where put in world file. when installed xcdroast it downgraded cdrtools because xcdrost needs an exact version of it, but it still were in world file.
when i tried to emerge -up world, portage told me to upgrade cdrtools, that is incorrect, because xcdroast require THAT version of that package, so it should be...blocked!
but this is not the real problem, because i fixed it removing cdrtools from the world file (it's unnecessary, because xcdroast depends on it)
but the problem still shows up in another situation!
i want to emerge anjuta, and when i pretend to do, portage virtually updates glib from 1.2 to 2.x (and i dunno why, because glib is not required in anjuta-1.0.0.ebuild, probably it depends from a dependancy (sorry for my english)) but this would BREAK xcdroast, that requires a specific version of glib.
isn't it strange?
am i doing something wrong?

tnx for help

[fifo]

It should be alright to let it install glib-2.x since it's in a different slot from glib-1.2, and hence glib-1.2 won't be autocleaned away.