こんな感じですか?
#include "user32.as"
winobj "button" , "a" , 0 , $50020009 , 200,20
winobj "button" , "b" , 0 , $50000009 , 200,20
winobj "button" , "c" , 0 , $50000009 , 200,20
pos ,ginfo_cy+10
winobj "button" , "1" , 0 , $50020009 , 200,20
winobj "button" , "2" , 0 , $50000009 , 200,20
winobj "button" , "3" , 0 , $50000009 , 200,20
winobj "button" , "4" , 0 , $50000009 , 200,20
oncmd gosub *wndmsg_Command,0x111
button "OK",*owari
hbutton = objinfo_hwnd(stat)
EnableWindow hbutton,0
stop
*wndmsg_Command
GetWindowLong lparam , 0xFFFFFFF0
if stat&0x9 : EnableWindow hbutton,1
return
*owari
end