diff --git a/controlsActions.pde b/controlsActions.pde
index cd50016..d596281 100644
--- a/controlsActions.pde
+++ b/controlsActions.pde
@@ -533,12 +533,14 @@ void numberbox_mode_changeMachineWidth(float value)
   clearBoxVectors();
   float steps = getDisplayMachine().inSteps((int) value);
   getDisplayMachine().getSize().x = steps;
+  getDisplayMachine().maxLength = null;
 }
 void numberbox_mode_changeMachineHeight(float value)
 {
   clearBoxVectors();
   float steps = getDisplayMachine().inSteps((int) value);
   getDisplayMachine().getSize().y = steps;
+  getDisplayMachine().maxLength = null;
 }
 void numberbox_mode_changeMMPerRev(float value)
 {
@@ -615,7 +617,7 @@ void button_mode_sendPenWidth()
   NumberFormat nf = NumberFormat.getNumberInstance(Locale.UK);
   DecimalFormat df = (DecimalFormat)nf;  
   df.applyPattern("###.##");
-  addToRealtimeCommandQueue(CMD_CHANGEPENWIDTH+df.format(currentPenWidth)+",END");
+  addToRealtimeCommandQueue(CMD_SETPENWIDTH+df.format(currentPenWidth)+",END");
 }  
 
 void numberbox_mode_changePenTestStartWidth(float value)
diff --git a/drawing.pde b/drawing.pde
index 07197a3..0e9f1aa 100644
--- a/drawing.pde
+++ b/drawing.pde
@@ -27,9 +27,9 @@
   https://github.com/euphy/polargraphcontroller
 */
 static final String CMD_CHANGELENGTH = "C01,";
-static final String CMD_CHANGEPENWIDTH = "C02,";
-static final String CMD_CHANGEMOTORSPEED = "C03,";
-static final String CMD_CHANGEMOTORACCEL = "C04,";
+static final String CMD_SETPENWIDTH = "C02,";
+//static final String CMD_CHANGEMOTORSPEED = "C03,";
+//static final String CMD_CHANGEMOTORACCEL = "C04,";
 static final String CMD_DRAWPIXEL = "C05,";
 static final String CMD_DRAWSCRIBBLEPIXEL = "C06,";
 static final String CMD_DRAWRECT = "C07,";
diff --git a/polargraphcontroller.pde b/polargraphcontroller.pde
index c6a8a54..8637405 100644
--- a/polargraphcontroller.pde
+++ b/polargraphcontroller.pde
@@ -685,7 +685,7 @@ void addEventListeners()
 
 void preLoadCommandQueue()
 {
-  addToCommandQueue(CMD_CHANGEPENWIDTH+currentPenWidth+",END");
+  addToCommandQueue(CMD_SETPENWIDTH+currentPenWidth+",END");
   addToCommandQueue(CMD_SETMOTORSPEED+currentMachineMaxSpeed+",END");
   addToCommandQueue(CMD_SETMOTORACCEL+currentMachineAccel+",END");
 }
@@ -819,6 +819,7 @@ Panel getPanel(String panelName)
 
 void drawImagePage()
 {
+  noLoop();
   strokeWeight(1);
   background(getBackgroundColour());
   noFill();
@@ -843,13 +844,21 @@ void drawImagePage()
 
   showGroupBox();
   showCurrentMachinePosition();
-  if (displayingQueuePreview)
-    previewQueue();
+  try {
+    if (displayingQueuePreview)
+      previewQueue();
+  }
+  catch (ConcurrentModificationException cme)
+  {
+    // not doing anything with this exception - I don't mind if it's wrong on the screen for a second or two.
+    println("Caught the pesky ConcurrentModificationException: " + cme.getMessage());
+  }
   if (displayingInfoTextOnInputPage)
     showText(250,45);
   drawStatusText((int)statusTextPosition.x, (int)statusTextPosition.y);
 
   showCommandQueue((int) getDisplayMachine().getOutline().getRight()+6, 20);
+ 
 }
 
 void drawMachineOutline()
@@ -1367,6 +1376,7 @@ void keyPressed()
 }
 void mouseDragged()
 {
+  loop();
   if (mouseOverControls().isEmpty())
   {
     if (mouseButton == CENTER)
@@ -1384,6 +1394,10 @@ void mouseDragged()
     }
   }
 }
+void mouseMoved()
+{
+  loop();
+}
   
 void mouseClicked()
 {