+<p><img src="textcolour.gif"></p>
+<p>The dialog box contains a slider, and two colour icons showing
+the text colour for dark backgrounds (left hand end of slider), and
+light backgrounds (right hand end of slider). Drag the slider to change
+the threshold for transitioning between dark and light background
+colours, and select either of the colour boxes to open a colour chooser
+to select a different text colour.</p>