Hey it's me again!
Last thread was a mess and with some old information so I thought I'll start fresh.
So the problem is that Steam Overlay does not work properly if the game is maximized. Meaning that if the application is for example 1280x720 and I set game to maximize it will add borders around the play area.
This is the setting I use in my game. What it does, it forces the Steam Overlay inside the play area, but all the links from the Steam Overlay are located inside the borders. So to activate browser for example, I will have to click randomly somewhere the border to activate it.
Now, in fullscreen it works perfectly as it won't add the borders.
So one possible solution would be to force scaled fullscreen when Steam Overlay is activated. I tried this with Ultimate Fullscreen but it did not work properly. It added delay of 2-3 seconds and closed randomly with shift. And I don't use UFS in my project anymore, so I would not want to add it.
Anyways, if you have idea how it could possibly work let me know!