please clarify you question:

In general, P3D has no problems with rects or ellipses. Although they are 2D they are just drawn correctly in a 3D context (in P3D).

what error are you getting when you try to run this?

www.morishuz.com
www.videoreactive.com
www.electrovision-cinema.com

I don't get a error, it just does't work when i put P3D in size.
I don't see rect or ellipse being drawn.

in setup you need to have

1.   typeIsDrawingtool = true;

where are your rects()?

here I show a part of the code (I took out the images because I don't have them)

It shows a rect with P3D

1.   .................
   
2.   typeIsDrawingtool = true;
3.   page.beginDraw();
4.   page.smooth();
5.   page.endDraw();
6. }
7. 
   
8. void draw() {
9.   if (typeIsDrawingtool) {
10.     println ("d1");
11.     d1.update();
12.   }
13. }
14. 
    
15. class Drawingtool {
16.   void update() {
17.     background(0);
18.     //    imageMode(CENTER);
19.     //    image(foto, width/2, height/2);
20.     //    imageMode(CORNER);
21.     //    image(menu, 10, 10);
22.     noStroke();
23.     rect(20, 20, 220, 19);
24.     //    image(page, 0, 0);
25.     //    image(menutwee, 10, 10);
26.     //    image(cirkelgroot, 91, 50);
27.     //    image(cirkelmidden, 108, 52);
28.     //    image(cirkelklein, 125, 55);
29.   }
30. }