WindowButtonMotionFcn producing strange errors

Hi, I have a program which has a WindowButtonMotionFcn executed within a loop to detect mouse movement. The loop plots stuff with axes and labels parameters as long as x=1 (while x=1...). I have another callback which stops the loop when I click on the background by setting x=0. Everything works fine but I still get those error codes at the end:

Error using handle.handle/get Invalid or deleted object.

Error using drawnow Error while evaluating figure WindowButtonMotionFcn

Error using handle.handle/get Invalid or deleted object.

Error using figure Error while evaluating figure WindowButtonMotionFcn

Error using handle.handle/get Invalid or deleted object.

Error using figure Error while evaluating figure WindowButtonMotionFcn

I have no idea where it is coming from and I would like to get rid of it.

Thank you!

[Geoff Hayes]

It may be helpful to post the code for the WindowButtonMotionFcn callback. Are you using global variables that may be shared between this callback and another? (Like the * WindowButtonDownFcn*?)

[Antoine]

There is a pushbutton that sets y=1. buttonno=uicontrol('style','pushbutton','string','NO','fontsize',16,'units','normalized','position',[0.120 0.875 0.06 0.08],'callback','y=1;');

Then, later in the code I have

if y==1 set(figureHandle,'WindowButtonMotionFcn','mil=get(ax(2),''CurrentPoint'');') end

Since the callbacks are not functions I don't think there could be global variables shared between them and the main code. I do have global variables for other callbacks/buttons.

After I have stopped the loop, I do other things like save plots, text files and then I get the errors.

[Antoine]

I managed to solve my problem by closing the figure window. Thank you for your help!

[Geoff Hayes]

That's an interesting way to have done the callback for your button - I wouldn't have thought to do it like that. Is y a global variable then? An alternative would have been to do something like

 buttonno=uicontrol('style','pushbutton','string','NO',...
                    'fontsize',16,'units','normalized',...
                    'position',[0.120 0.875 0.06,0.08],...
                    'callback',@noButtonCallback);

Then have the callback defined as

 function noButtonCallback(hObject,eventData)
     set(figureHandle,'WindowButtonMotionFcn',...
         'mil=get(ax(2),''CurrentPoint'');')
 end

With another callback in place of the 'mil=get(ax(2))' function. I guess that mil is another global variable? As is ax and figureHandle?

(Event my callback won't work without declaring the global variable of figureHandle.)

Since the * WindowButtonMotionFcn* is just mil=get(ax(2),''CurrentPoint''), then the ax may become undefined/invalid/empty when the loop stops.

It is kind of challenging to debug this sort of problem since you can't really step through the callbacks to see how they are being evaluated.

I urge you to consider using actual functions as your callbacks (similar to noButtonCallback above) so that when you encounter a problem, you can put in a breakpoint at the function that is failing and step through its code to see what is going wrong.