The frame control window procedure responds to this message by first sending a TBM_SETHILITE message to the FID_TITLEBAR control, if it exists, to highlight or unhighlight the title bar. If the style is FCF_DLGBORDER, the border is redrawn in either highlighted or unhighlighted state, as necessary.

It then sends the WM_ACTIVATE message to the FID_CLIENT window.

Then it sets ulReserved to 0.