Here is what it looks like in the beginning when I haven\'t added any imagespan chips -
Chances are the ImageSpan changes the lineheight after it's added. If you set a line height bigger than the imagespan, I have a feeling your cursor will remain constant size (but still large). At this point you can add padding to shrink it down to the smaller size you want and it should remain constant.
(I don't have a chance to test what I just wrote, so it's just a theory)