When dragging the camera, the cursor is supposed to stay in the same place it was when you first pressed the mouse button.
But sometimes, if you start with the mouse over a NPC/enemy hit-box, the cursor will move. Depending how fast you move the cursor with it over a NPC, the cursor position will jump.
Which leads to:
At an extreme, it can go all the way to the screen border, and…
In window mode, it will catch the border and re-size the window.
Also, I could swear this happens in full-screen mode, but can’t replicate it anymore: accidentally selects a target if an enemy is on the screen border where the cursor jumped to.
Like the old bug I linked to, it also happens if the mouse wasn’t on NPC when you pressed the button, but is on NPC when you release the button.
The cursor won’t be where the player expects it to be, and he loses track of it and has to move it around wildly to find it again.
Expected behavior:
It should behave the same as if you start with the cursor on blank space: the cursor will be in the same place when you release the button.
I didn’t notice the bug until now because I used to play full-screen
I only noticed it when I started playing in window mode and the mouse kept catching the window border and re-sizing the game.
This bug could be the reason why a lot of people complain they lose track of the cursor, even asking if there’s a mod that makes the cursor brighter so it’s easier to see. Generally you unconsciously remember where the cursor is even if you can’t see it, but since it jumps around if your mouse was over an NPC, the cursor is not where you expect it to be anymore.
You can also accidentally bring up the Hero panel if you click and drag the left mouse button over the daily achievements on the top right corner of the screen, though you were actually trying to drag the camera instead. It should only open it if you don’t drag the mouse.
This also makes the cursor jump positions, though if you use the right mouse button instead, it doesn’t jump.