Hi - I am new to Processing, so please bear with me.

My first attempt at a sketch is intended to allow a box to be dragged around the screen. It works OK until I try to drag the box rapidly and then it gets left behind. I would be grateful for any suggestions as to where I have gone wrong.

Code:

1. DragBox drgbx;
   
   void setup()
   {
     size(700, 700);
     background(210);
     drgbx = new DragBox(25, 25, 100, 100);
   }
   
   void draw()
   {
     background(210);
     drgbx.boxDisplay();
     //move box with mouse
     rect(drgbx.boxX, drgbx.boxY, drgbx.boxW, drgbx.boxH);
   }
   
   class DragBox
   {
     float boxX;
     float boxY;
     int boxW;
     int boxH;
     boolean msOver = false;
     boolean msPressed = false;
    
     // constructor
     DragBox(float tmpBoxX, float tmpBoxY, int tmpBoxW, int tmpBoxH) {
       boxX = tmpBoxX;
       boxY = tmpBoxY;
       boxW = tmpBoxW;
       boxH = tmpBoxH;
     }
    
     boolean mOver()
     {
       if (mouseX >= boxX && mouseX <= boxX+boxW &&
           mouseY >= boxY && mouseY <= boxY+boxH) {
             msOver = true;
             return msOver;
             } else {
               msOver = false;
               return msOver;
               }
     }
    
     boolean mPressed()
     {
      if (mousePressed) {
            msPressed = true;
            return msPressed;
            } else {
              msPressed = false;
              return msPressed;
            }
   
     }
    
     void boxDisplay() {
       //code to display box in specific location
         
       mOver();
       mPressed();
       if (msOver) {
         if (msPressed) {
           //println("Mouse Over and Mouse Pressed");
           //calculate mouse movement and move box the same amount
           float posXDif = mouseX - pmouseX;
           float posYDif = mouseY - pmouseY;
           //update local positional variables based on mouse location
           boxX = boxX + posXDif;
           boxY = boxY + posYDif;
         }
       }
     }
   }