I'm pretty sure that's just a problem with windows. I've used dual monitors for years and that's always happened, weirdly though if there's a video playing on the browser I can see it fine, just not pages with mostly text.

Ye it updates when something moves

Try this dirty fix: Open tf2, in windowed mode, open your other windows, tab back into tf2 and set it to fullscreen. I do this when I'm watching movies on my second screen while playing and the renderer doesn't work when I open tf2 in fullscreen.

Thats way too much trouble, thanks for info tho

Full screen tries to take over the whole video display which can causes problems for second monitors. That's why mumble overlay has problems.

Try using DisplayFusion. I use it and I have no problem fullscreening on dual monitors.

Works so far

Wtf, all you have to do is change a setting in the tf2 menu twice, that's way quicker than installing a software lol

I would have to do that every time i open tf2 or alt tab?

Depends if it fucks up when alt-tabbing, for me it usually works after being successfully in fullscreen once. So I just have to let tf2 start windowed by default and then change to fullscreen every time I open (and happen to watch something on the second monitor with a renderer that doesn't like tf2).

I was having this problem today. Seemed to only happen when i had my taskbar on the monitor not running tf2

I had this problem before, what I did was go to display options and switch the monitor to the other side. You have to move your mouse the opposite way to get to your other monitor but it you get used to it and it fixed the problem for me.