Tooltip issues:
- Sometimes it's impossible to read a status effect tooltip - when you hover a mouse above it no message appears or appears message on another status effect. If you resize the game window to any size and then revert, tooltip appears.
- Often it's impossible to check a creature linked in the chat. Yet you can open global chat window(h) and see the tooltip without problems
- When targeting a spell with a keyboard, instead of the creature tooltip you're targeting on, you get random tooltips under them like a creature linked in chat half an hour ago or a boss you just killed
There are also numerous other small issues that primarily affect newcomers due to affecting general interface responsivness:
- Dragging abilities on the hotbar is really inconvinient. When you start dragging an icon you never know where it will land if you release the mouse: will it vanish or swap with other ability. This is especially noticeable when you drag it, then scroll a few pages away(page up/page down) and then try it to assign to, let's say, alt+1. It's almost impossible to guess the right position, because you don't know exact borders of the hotbar icon grid and additionally you have to figure out each hotbar spot's hotkey since they are not displayed unless they have an ability in them.
- Page up/page down scrolls hotbar by one half? Why not scroll it one full page? Also i suppose it would be better to have two small arrows to do it via mouse and a number with currently viewing page.
- Hotbar size scales in a wrong way with "icon hotkey toolbar size option" enabled:
[spoiler]

With red I marked unwanted space that should be removed
- It has been probably requested numerous times, but Tome has really a lot of hotkeys and it would be really desireable to have numerous rows of them visible at once. For example two rows: 12 regular hotkeys 1, 2, 3.. = and 12 shift+1, shift+2, ... , shift+= hotkeys
- Viewing long race description on character creation screen or long ability description on levelup window can be really frustrating
[spoiler]

When hovering over an ability with a long desription I have to move mouse cursor following the green line Really carefully so that some other tooltip won't appear instead of Dream Hammer's and then when my cursor is finally over its description, I can use mouse wheel to scroll it. Really frustrating experience.
DG, I have spent 200+ hours in your game and I can cope with any bugs it has because it's absolutely great in every other aspect. But newcomers, potentially steam are always severely affected by these small usability issues.