Draws a rectangle in the style used to indicate that the rectangle has the focus
_WinAPI_DrawFocusRect ( $hDC, $tRECT )
|$hDC||A handle to the device context.|
|$tRECT||$tagRECT structure that specifies the logical coordinates of the rectangle that is to be drawn.|
The _WinAPI_DrawFocusRect() is an XOR function, so calling it a second time with the same rectangle removes the rectangle from the screen.
Search DrawFocusRect in MSDN Library.