MCI_UNDO - Description

This message undoes the operation most recently performed by cut, paste, or delete.

ulParam1 (ULONG)

This parameter can contain any of the following flags:

MCI_NOTIFY

A notification message will be posted to the window specified in the hwndCallback parameter of the data structure pointed to by the pParam2 parameter. The notification will be posted when the action indicated by this message is completed or when an error occurs.
MCI_WAIT
Control is not to be returned until the action indicated by this message is completed or an error occurs.

pParam2 (PMCI_GENERIC_PARMS)

A pointer to the default media control interface parameter data structure.

rc (ULONG)

Return codes indicating success or type of failure:

MCIERR_SUCCESS

The UNDO was successful.
MCIERR_INVALID_DEVICE_ID
The device ID is not valid.
MCIERR_INVALID_FLAG
Flag (ulParam1) is invalid.
MCIERR_INSTANCE_INACTIVE
The device is currently inactive. Issue MCI_ACQUIREDEVICE to make the device context active.
MCIERR_INVALID_CALLBACK_HANDLE
Given callback handle is invalid.
MCIERR_CANNOT_UNDO
Undo is not possible in the current state.

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