Different behaviors with mouse+button in PIE/standalone


When i overload my system by spawning too much actors, it slows differently in PIE and in standalone/packaged game.

In PIE the slowing is uniform: keyboard displacements (aswd) and mouse rotation are equally slowed down and the result behavior is understandable for a user.

But in standalone and packaged game, although the aswd displacements are fine, the mouse rotation is totally irregular, giving a very chaotic and confusing behavior.

As it’s quite complicated to describe, i made a short video showing the problem.

mouse problem

As you’ll see, it seems that the GetMousePosition function, although being called, seems to stop updating the mouse position in standalone mode, even when the rest seems to go on all right.

I know the obvious answer would be “just don’t overload your system” :slight_smile:

But what i’m showing here is merely an extreme case: even without overloading my system, i get some glitches in rotation when playing in standalone that do not occur while playing in editor.

My problem seems related to those two problems described here:

but they seem to have the same problem both in PIE and in standalone, while my problem is precisely that i have a different behavior in both cases (and i would like to have everywhere the PIE behavior: uniform and understandable slowing).

I should add some useful info here:

  • it’s not related to rotation only, i get the same behavior with my rectangle selection and suspect that the problem is related to using the mouse position while pressing a mouse button at the same time
  • i think the repro steps should be: 1/ define some mouse behavior involving drag + mouse button clicked, 2/ overload your system any way you want, and 3/ try the mouse in PIE and standalone.

Thanks !


Hey -

I tried to mimic the slowdown you mentioned by capping my framerate extremely low (tried a fixed rate of 15fps as well as a smoothing range of 0-1 fps). With the mouse position printing on Tick, testing PIE window vs standalone did not show any update messaging being missed in the standalone version. Fewer messages were printed because there were fewer updates, but each updated printed the current position as expected. If you’re able to provide step-by-step setup instructions to help me test the behavior locally, or provide a sample project that demonstrates what you’re seeing it will help me investigate the issue on my end.

Hey ,

I could finally find the time to make you a sample project reproducing the problem.

You’ll find it here:


And here’s a short video to show you how it works:


Thanks !


Hey -

Thank you for the sample project. I have reported the difference in behavior here: Unreal Engine Issues and Bug Tracker (UE-45892) . You can track the report’s status as the issue is reviewed by our development staff. Please be aware that this issue may not be prioritized or fixed soon.


Hey got the same problem here in 4.16.3 !

But when I hide the cursor by setting bShowMouseCursor at false in player controller it’s completly fixed (again the bug is happening only in standalone) ! Seems to me that it’s related maybe to the high precision by the look of this code :

if ( bCursorHiddenDueToCapture || !bShouldShowMouseCursor )