c - win32 Textbox and AnimateWindow -

i'm making native win32 application , use animatewindow fadein window. works except couple textboxes have in window not drawn until invalidaterect call after fadein. msdn doc says wm_printclient message must handled custom controls draw correctly, isnt needed common controls. why text controls not work correctly? , how implement wm_printclient text controls? here's tried no success in wndproc function:

... case wm_printclient: sendmessage(htextctl, wm_print, wparam, prf_owned); break;