question: public void registerFontMetrics ( String name , Font font , float lineHeight ) { HtmlFontMetrics metrics = getFontMetrics ( font ) ; fontMetrics . put ( font , new HtmlFontMetrics ( font , lineHeight , metrics . emwidth ) ) ; }
target:  Registers metrics for the specified font in the specified style and size. This overrides the default font metrics calculation (which is hacky and inaccurate). If you want to ensure somewhat consistent font layout across browsers, you should register font metrics for every combination of font, style and size that you use in your app.