When TERM is defined to "kterm" (e.g. aterm compiled with cjk USE flag), screen doesn't know how to handle the terminal, incorrectly guessing the size of the terminal and writing to the terminal in ways that make for confusing and decidedly broken appearances. Try it: # USE="cjk" emerge aterm $ aterm -e screen and try to use screen as you would normally. Strange things happen, far too many to detect or list.
Forgot to mention version numbers. Screen 4.0.2, aterm 0.4.2-r9.
The problem is not in kterm but aterm. kterm has status line but aterm doesn't, and screen tries to use status line if supported (by judging from TERM). If this is not what you desired, set TERM to something else or talk to aterm developer to change to not set aterm's TERM as kterm.
