[lmi] A GUI test for pasting

[Greg Chicares]

Vadim, would you please look at this change I just made:
  http://cvs.sv.gnu.org/viewvc/lmi/lmi/main_wx.cpp?r1=1.91&r2=1.92
and tell me what I'm doing wrong? I'm trying to follow a
casual sketch you laid out long ago in an off-list email
from 2006-08-12T01:25Z (which is why I ask you by name--not
to exclude Vaclav if he sees this first) but I can't get the
paste handler to change the text from its initial contents.