uses Registry;
procedure TForm1.Button1Click(Sender: TObject);
var
Reg:TRegistry;
KeyName: String;
ValueStr: String;
begin
Reg:=TRegistry.Create;
try
Reg.RootKey:=HKEY_CLASSES_ROOT;
KeyName:='htmlfile/shell/open/command';
if Reg.OpenKey(KeyName, False) then
begin
ValueStr:=Reg.ReadString('');
Reg.CloseKey;
Label1.Caption:=ValueStr;
end
else
ShowMessage('No default webbrowser !');
finally
Reg.Free;
end;
end;