Code:
Sub Sendtext(txt As TextBox)
Dim IMClass As Long, RICHEDIT As Long
IMClass& = FindWindow("IMClass", vbNullString)
RICHEDIT& = FindWindowEx(IMClass&, RICHEDIT&, "RICHEDIT", vbNullString)
RICHEDIT& = FindWindowEx(IMClass&, RICHEDIT&, "RICHEDIT", vbNullString)
Call SendMessage(IMClass&, WM_SETTEXT, ByVal txt.Text, 0&)
End Sub