This is my first post here, so far - thank you for this wonderful community! I do tend to spend a lot of time here and find a lot of the answers around :) However, I seem to have troubles finding the answer of this specific question, and with my thesis submission knocking on the door I'm getting kinda desperate :)

Here it goes:

I am trying to get a few sketches stick together into a linear flow style application. The way I imagine it is the following:

2. First  screen_first;
3. Second screen_second;
4. int stage = 0;
5. 
   
6. void setup()
7. {
8.   size(860, 600);
9.   colorMode(HSB, 360, 100, 100);
10.   smooth();
11.   screen_first = new First();
12.   screen_second = new Second();  
13. }
14. 
    
15. void draw()
16. {
17.   background(0);
18.   switch(stage)
19.   {
20.   case 0:
21.   screen_first.draw();
22.   break;
23.   case 1:
24.   screen_second.draw();
25.   break;
26.   }
27. }
28. 
    
29. void mousePressed()
30. {
31.   stage++;
32.   if (stage == 2) stage = 0;
33. }
34. 
    
36. class First 
37. {
38.   First()
39.   {    
40.     size(860, 600);
41.     colorMode(HSB, 360, 100, 100);
42.     smooth();
43.   }
44. 
    
45.   void draw()
46.   {
47.     background(240, 40, 40);
48.     fill(300,100,90);
49.     rect(20,20,100,100);
50.   }  
51. }
53. 
    
54. class Second
55. {
56.   Second()
57.   {
58.     size(860, 600);
59.     colorMode(HSB, 360, 100, 100);
60.     smooth();
61.   }
62.   void draw()
63.   {
64.     background(50, 80, 40);
65.     fill(100,90,90);
66.     rect(50,120,200,200);
67.   }
68. }

Now, I did my research here first - there seems to be a lot of ways to accomplish the task using extra frames, but that's not what I would like to use if possible. The idea is that there is no main control screen,  but rather toggling (linearly switching to) 4 sketches (that I am working on separately right now). 

If I am conceptually wrong about this, please do advise me to what a better workflow might be. 

Thank you in advance!

Deyan