I have tried to send message to the TreeView control to the some external application control. It works fine for messages like TVM_GETNEXTITEM, TVM_SELECTITEM, but it failed for TVM_GETITEM call! The difference is, as I can see it, the TVM_GETITEM need to fill some structure which address I pass as LPARAM SendMessage() call. I get the FALSE as SendMessage(hTV, TVM_GETITEM, 0, &TVItem). Any suggesions? Thanks.