Limiting the opening of the windows

As you know the windows in CSR can open until 90 degree which can be quite a hazard.

I am looking for a way to limit it to about 10 degree, as I have children in the apt.

Has anyone manage to do this with the windows supplied ?

Thanks in advance.

suggest u install window grille at all windows (other than those window you can't open) like what I hv done to prevent any accident from happen.

I am trying to avoid putting grills.

That is why I am looking for some options.

Thanks for the input.

there should be some child-safety devices on the market that you might want to consider to install on your windows, to prevent your children from opening it unnecessarily and as a result, placing themselves at a risk.

http://www.safebeginnings.com/

It's a US company but online store and might give you some ideas for solution