In the patch notes, in the resolution section, it says to report issues we come across with the new resolution/UI Optimization changes. I am submitting my issues here as I don't know where else to report them. I've always played Maplestory on 1920 x 1080. However, my monitor does support 1440p, so I wanted to try that option.
In 1080p, the UI is very smooth when using "UI Optimization". It doesn't take up the large majority of your screen, and the UI looks very high definition. Unfortunately, in 1440p, both with and without "UI Optimization", the UI takes up a MAJORITY of the screen, the UI looks blurry, and overall, it looks almost identical to 720p. Screenshots are shown here for reference: https://imgur.com/a/sBQ7Q9S
In my opinion, 1440p should look more high definition than 1080p. In general for other games that I've played, 1440p usually makes the UI smaller and clearer. Unfortunately in Maplestory, it looks the opposite.
I think another option that could be useful is to allow us to have "options" to make the UI smaller or larger regardless of the resolution. (Many games allow for a sliding bar to adjust UI size independent of the resolution chosen).
Last thing which is not as important but would be nice: the chat window never moves with the resolution changing. It would be nice for it to always place itself at the bottom lefthand side (or have it place to the same area relative to the new resolution), so that I don't have to manually drag it back down. This issue also happens when you go into gameplay sections that require a lower resolution (for example, when doing the fishing event in Iden, your resolution goes down. When you come out of the event at your higher resolution, the chat bar is now higher than it was before.
I hope this information can help solve the issue. I would really like this to work as the new "fullscreen" option by hitting alt + enter essentially creates a "fullscreen borderless" mode so I can tab in and out easily of Maplestory.