Hi Sébastien,

As far as I know there is no way to disable that maximize icon.

Kind regards,

Gareth

Dear 

One thoguht that might help you solve it , 

when you open your subview , right cilck the maximize button and inspect element .

only if you can find a unique attribute value for this button , then you might wanna give it a try and hide it/disable it in jquery statement 

for example when u inspect element on the maximize button of the subview 

<button type="button" class="maximizeButton"/> <--- this is an example which is not same as your button , just using for the sake of an explaination

after that add literal data label inside of your subview and write java script / jquery inside of it like:

$(".maximizeButton").css("display","none");

so the things you need to check before proceeding .

1-finding unique attribute for this maximizing button to use it in your jquery selector .

2-adding literal data label to execute your jquery code in the subview .

Hope it helps!

Regards.