If a game is run in the standalone editor and the FPS drops to ~20-30 FPS, pressing an event such as LMB and returning the mouse position on tick will cause the tick to jump inconsistently.


This bug is extremely difficult to reproduce. During testing it reproduced once out of ~12 attempts.

Steps to Reproduce

1. Download, unzip, and open attached project.
2. Press play to play in standalone mode
3. Using RMB and repeatedly dragging, turn the camera to face the floor, this causes the framerate to drop.
4. Press and hold LMB and move the mouse on screen


If error occurs, the mouse position will report inconsistently, jumping between values instead of smoothly moving with the mouse cursor.


Tick accurately shows mouse position every frame and smoothly moves between values.

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Won't Fix
ComponentUE - Editor - UI Systems - Slate
Affects Versions4.10
CreatedDec 11, 2015
ResolvedDec 15, 2015
UpdatedJul 14, 2021