dgui - Button continually repainting

[Mike James via Digitalmars-d-learn]

Hi.

I've created a graphic button as per this example on the dgui 
website:

import dgui.all;

class MyForm: Form
{
	this()
	{
		text = "An Exception was thrown...";
		size = Size(130, 100);

		// Or use `Bitmap.fromFile`:
		auto img = new Bitmap(90, 15, SystemColors.yellow);
		auto pen = SystemPens.blackPen;

		with(new Button())
		{
			bounds = Rect(10, 10, 100, 25);
			parent = this;
			paint.attach((s, e)
			{
				e.canvas.drawImage(img, 5, 5);
				e.canvas.drawLine(pen, 5, 10, 95, 10);
				e.canvas.drawLine(pen, 10, 5, 10, 20);
			});
		}
	}
}

int main()
{
	return Application.run(new MyForm());
}

and added a writeln("paint") in the paint.attach to show when the 
button is repainting. When the form with the button is visible 
the button is being continually repainted. Is this a 'feature' of 
dgui or is there a flag to set to only re-paint when the button 
is invalidated?

Regards, -=mike=-.