Sample Download : http://code.msdn.microsoft.com/CppSendWMCOPYDATA-f75bc681
This code sample demonstrates sending a custom data structure (MY_STRUCT) to the receiving Windows application (CppReceiveWM_COPYDATA) by using SendMessage(WM_COPYDATA). If the data structure fails to be passed, the application displays the error code for diagnostics. A typical error code is 0x5 (Access is denied)caused by User Interface Privilege Isolation (UIPI). UIPI prevents processes from sending selected window messages and other USER APIs to processes running with higher integrity. When the receiving application (CppReceiveWM_COPYDATA) runs at an integrity level higher than this sending application, you will see the “SendMessage(WM_COPYDATA) failed w/err 0x00000005” error message.
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