Hi - I am pretty new to processing and am learning as I am going. I am working on a small project and am stuck on one thing. I am displaying a matrix of squares, all colored differently using a formula based on their position. When I click on a square, I want it to turn blue and retain that color until I click on it again. I also want to be able to select multiple squares. Sometimes it works (a square is selected, but it is not colored blue - but a different color) sometimes it does not and I can't figure out the problem. Any help, tips, or pointers would be appreciated. Here is my code:

1. int canvasWidth = 500;
2. int canvasHeight = 500;
3. int matrixSize = 6;
4. boolean[][] squaresArray = new boolean[matrixSize][matrixSize];
5. 
   
6. void setup() {
7.   int i = 0;
8.   int j = 0;
9.   size(canvasWidth, canvasHeight);
10.   noStroke();
11.   smooth();
12.   for (i=0; i < matrixSize; i++)
13.     for(j=0; j < matrixSize; j++)
14.         squaresArray[i][j] = false;
15. }
16. 
    
17. boolean mouseOverRect(int x, int y, int w, int h) {
18.   return (mouseX >= x && mouseX <= x+w && mouseY >= y && mouseY <= y+h);
19. }
20. 
    
21. void draw() {
22.   background(100);
23.   int rX = 0;
24.   int rY = 0;
25.   int rW = 30;
26.   int rH = 30;
27.   int i = 0;
28.   int j = 0;
29. 
    
30.   for (i=0; i < matrixSize; i++)
31.     {
32.       rY += 50;
33.       for(j=0; j < matrixSize; j++)
34.       {
35.         rX += 50;
36.         if (mouseOverRect(rX, rY, rW, rH))
37.           {
38.             if (mousePressed)
39.             {
40.               squaresArray[i][j] = !squaresArray[i][j];    // change state of square
    
41.               if ( squaresArray[i][j] )
42.                 {
43.                   fill(0, 0, 255);  // square has been clicked and is now True - fill with blue
    
44.                 }
45.                 else
46.                 {
47.                    // revert to unclicked color:
48.                   fill( map(rX,0,canvasWidth,0,255), map(rY,0,canvasHeight,0,255), 100); 
    
49.                 }
50.             }
51.           }
52.         else {
53.           if ( !squaresArray[i][j] )
54.                 {
55.                   // square is false, so fill with unclicked color
    
56.                   fill( map(rX,0,canvasWidth,0,255), map(rY,0,canvasHeight,0,255), 100);
57.                 }
58.           }
59.         rect(rX, rY, rW, rH);
60.       }
61.       rX = 0;
62.     }
63. }