Yet another little bug and i need help...

So today i've encountered 1 of many little bugs in win10, when something goes wrong no one knows why. In Alt-tab interface, the white frame shows which window will be active after you release those buttons and mine stay the same, so i have to manually switch with mouse which is kinda annoying. Found out it happens only with fullscreen/borderless apps  (games in my case) and if i switch them to windowed mode, it works fine. Another thing that work incorrect is switching between desktops: when i open this interface and hover FROM taskbar it just closes immediately. Raging from all of this, i randomly dragged my taskbar from top to bottom and pressed 1 more time on switch desktop and it worked fine! Then i tried alt-tabing and it worked too! Also, i found out that switching windows doesn't make the new window active, when playing WoW. So with this bug it works something like this: do your things in browser, alt-tab to the game and it's not the active window so you need to manually press on it to make it active. No idea how it started and how to fix it, so i need someone's help. And yes, yesterday it worked fine. Rebooting computer doesn't help.