procedure ClearReadingHighlight;
Reading highlight rectangles are supplied in page coordinates and painted over the requested page. This is intended for the current paragraph, heading, table cell, or line being spoken
Clear the highlight when playback stops or when the application moves to another fragment. ReadingHighlightColor controls the overlay colour
if Length(Content.Fragments) > 0 then
PdfView1.SetReadingHighlight(Content.Fragments[0].LineRects, Content.Page);