Sent to a WIMMessageCallback function to indicate an update in the progress of an image application.
WIM_MSG_PROGRESS wParam = (UINT) dwPercent; lParam = (UINT) dwTicksRemaining;
[in] Specifies the percentage of the image that was already applied.
[in] Specifies the estimated number of milliseconds until the image application is complete.
Your routine must return WIM_MSG_SUCCESS.
Progress estimates typically increase during the early stages of an image apply and later decrease, so the calling process must handle this as appropriate.