I can't believe nobody has posted about this yet, or I can't find it. Anyways, my problem is that at 1280x720 resolution, the comparison popup goes off the screen.
The first screenshot shows it at 80 something text scale.
https://steamuserimages-a.akamaihd.net/ugc/927057751319916965/088E052E5D744C34DBB3A43999B06EFE7F2FFC53/
The second screenshot shows it at my preferred setting of 120.
https://steamuserimages-a.akamaihd.net/ugc/927057751319917129/0188363DE7058F129EC0A93B28D6464E66926438/
It also happens in the inventory screen, except vertically.
https://steamuserimages-a.akamaihd.net/ugc/927057751319936210/141762D8271889E3EB4223C10FB96FAD84FD0105/
In both cases I'm able to get around it via the compare function (or in the case of dual wield, I remove one item), though the screen is a bit crowded, heh.
https://steamuserimages-a.akamaihd.net/ugc/927057751319949145/81E06B0998803EE64F543107B97DBF3B6E8AC828/
Also, not everything suffers from it horizontially, it's things like weapons that make the window go wide which are more prone to it.