Author: Jonas Bilinkevicius

I have a custom dialog. So far I have set the font to Verdana. What I would like to 
do is to be able to set the dialog font to the one that's currently being used.

Answer:

This code sets the font of dialogs system-wide to Verdana:

procedure TForm1.Button1Click(Sender: TObject);
var
  ncm: TNonClientMetrics;
begin
  ncm.cbSize := SizeOf(TNonClientMetrics);
  {get old non client metrics}
  SystemParametersInfo(SPI_GETNONCLIENTMETRICS, SizeOf(TNonClientMetrics), @ncm, 0);
  {lfCaptionFont - regular captions
  lfSmCaptionFont - small captions
  lfMenuFont - menus
  lfStatusFont - status bars
  lfMessageFont - message boxes}
  ncm.lfMessageFont.lfFaceName := 'Tahoma';
  {set new non client metrics}
  SystemParametersInfo(SPI_SETNONCLIENTMETRICS, SizeOf(TNonClientMetrics), @ncm, 0);
end;