Issue with size adjustment after resizeEnd event

[x3p8z]

Hello everyone,

I have a problem that is demonstrated in the following example:
http://codepen.io/x3p8z/pen/BKXBPx

In this example, only line 21 in the JS file is changed from the original demo to:
$scope.dynamicSize.height = 50;

The expected behavior is that after every vertical resize, the size is reset to 50 px. This works the first time, but not for the following resize operations. While the value in the bottom left box is shown correctly as 50 all the time, the box has a different dimension.

I appreciate any inputs and hints how to achieve the desired behavior!