Added MarkDirty implementation for MultiLine Edit controls.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@24044 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/os2/textctrl.cpp

@@ -712,6 +712,10 @@ bool wxTextCtrl::IsModified() const
 
 void wxTextCtrl::MarkDirty()
 {
+    if (m_bIsMLE)
+        ::WinSendMsg(GetHwnd(), MLM_SETCHANGED, MPFROMLONG(TRUE), 0);
+    else
+        // EM controls do not have a SETCHANGED, what can we do??
         wxFAIL_MSG( _T("not implemented") );
 }