Don't really know a lot about this, but I do know that the full-row select parameter is set internally by MaxGUI when the list box is created. In win32listbox.cpp:
SendMessage( hwnd,LVM_SETEXTENDEDLISTVIEWSTYLE,LVS_EX_FULLROWSELECT,LVS_EX_FULLROWSELECT);You'll probably need to unset this LVS_EX_FULLROWSELECT parameter, but other than that, I don't really know.