Attach click-event to Figure

I want to update a Figure in a loop and attach a mouse-click-event. The following code works fine:

Function:

function OnMouse(hObject,~)
axes_handle = gca;
pt = get(axes_handle, 'CurrentPoint');

clicked_x=pt(1,1)
clicked_y=pt(1,2)

Main:

im = rand(500,500);
f=figure(1);
set(f,'WindowButtonDownFcn',@mytestcallback)
imshow(im)

But if I update the figure in a loop, the click is (nearly) never detected:

for i = 1:100
    im = rand(500,500);
    f=figure(1);
    set(f,'WindowButtonDownFcn',@mytestcallback)
    imshow(im)
    %pause(1)
    %pause(0.001)
end

Including a pause of 0.5 seconds solves this problem, but I cannot afford to make pause-time > 5 ms. How can I update my figure through a loop and attach a click-event which always will be detected?

Answer 1

[Walter Roberson]

f=figure(1);
set(f,'WindowButtonDownFcn',@mytestcallback)

for i = 1:100
    im = rand(500,500);
    imshow(im)
    drawnow();    %allows display to update _and_ allows button callback to be processed
end

[Brian Wolin]

I found that when running Walter's code, I get unusual behavior of when the callback executes or not. When clicking on the image, the callback executes maybe 25% of the time. When clicking inside the figure, but outside the image, the callback executes every time.

Any ideas why this might be the case and/or how to ensure the callback executes every time when clicking on the image/axes?

Here is my specific the callback function code, but I don't think this part matters for the behavior I describe.

function mytestcallback(src,~)
    pt = get(gca,'CurrentPoint');
    fprintf('Clicked: %d %d\n', pt(1,1),pt(1,2));
end

Edit: Also note that this behavior only manifests while the loop is running. Afterwards, clicking on the image is just as reliable as clicking elsewhere.