I have problems with some buttons on my 2nd scene, but not in the first. One important differance between the scenes is that in the first scene I add the buttons from the start, but in the second I add them after a while. In the first scene they are far to the left on screen, in the second they are close to the middle. If I click a bit to the right of the buttons in the scene where they are not working, I pop out of fullscreen mode.

Unity Version is 5.3.0f4.

Same issue here!

Same issue for me... :-(

There's also this issue

http://issuetracker.unity3d.com/issues/standalone-inconsistent-direct3d-behavior-with-non-native-resolution-on-fullscreen-builds

which I believe is related.

The 5.1.3 patch 3 from 11 September should include a fix for that:

(722983) - Fixed broken positioning of render when upscaling to native desktop resolution in full screen mode (Direct3D 9 and Direct3D 11).

But for example a 4:3 game is still stretched to fit a 16:10 desktop resolution in D3D11 full screen mode and the mouse position is still incorrect. It seems nothing has changed in that regard.

Same issue here. NOT fixed in 5.2 despite the "Duplicate issue" claiming its fixed.

Same problem on Unity 5.2.
I use NGUI for my project, and you ?

Same problem here, with Unity 5.1.2f1.

I've had this issue for awhile now with the uGUI (months it seems). I'm currently using Unity 5.1.1p1 and the issue is still there. Please fix!

I'm somewhat surprised this is even a problem for a game engine, considering buttons being detected properly on a user interface (in fullscreen mode) is essential to about 99% of games I've seen. Resolution and GUI issues using dx11 in Unity has been a terrible experience up to this point.

Having the same problem here, a quick fix would really be nice. For now I just limited the resolution to only allow 16:9, but that's no option to stick with.

This problem plays and I and friends.
And in the last fifth version, and 4.6.7f1