A handle to the window whose UIPI message filter is to be modified.
The message that the message filter allows through or blocks.
The action to be performed, and can take one of the following values:
Allows the message through the filter. This enables the message to be received by hWnd,
regardless of the source of the message, even it comes from a lower privileged process.
Blocks the message to be delivered to hWnd if it comes from a lower privileged process,
unless the message is allowed process-wide by using the ChangeWindowMessageFilter function or globally.
Resets the window message filter for hWnd to the default. Any message allowed globally
or process-wide will get through, but any message not included in those two categories,
and which comes from a lower privileged process, will be blocked.
pChangeFilterStruct [in, out, optional]
Optional pointer to a CHANGEFILTERSTRUCT structure.