MouseLeave doesn't fire if you move mouse fast

Bug Reports Engine Bugs
#41

It seems that there’s a bug where if you move the mouse quickly from one button to another, the new button will fire MouseEnter before the old button fires MouseLeave. If you have a system where you have a variable storing the currently hovered button, this will cause the following behavior:

  • You’re hovering button A.
  • You move the hover to button B.
  • B.MouseEnter fires, you set hoveredButton to B.
  • A.MouseLeave fires, you set hoveredButton to nil.
  • hoveredButton is now nil despite B still being in the hover state.

We’ll look into fixing it.

2 Likes
#42

A fix would be greatly appreciated! My game uses animations that rely on that and it would just look better if they worked more often

#43

It looks like for your particular game, this isn’t the issue.

There are calls to TweenSize for MouseEnter and Leave, and the override boolean is set to false. If you set this to true, it works. This is because without setting override, the tweens can run simultaneously and the state gets messy. I’d also recommend using TweenService instead as the old Tween methods will be deprecated in the future.

8 Likes
#44

Cool. I had no idea it was my fault this was happening. I’m glad I can fix it.

1 Like
#46

Thanks for the advice! I was stuck on this for a whole month, but the whole time I had override set to true! You helped me fixed my game!

#47

Sorry for the necropost, but it appears I’m having an issue similar to that of MouseEnter being called before MouseLeave when dragging the mouse quickly to another ui element.

Sure, I could reorient my code to a solution that does not depend on MouseLeave to be called on the first ui element before MouseEnter is called on the second ui element, but it should be expected that your mouse leaves the first element before entering the second element.

The error shown in a GIF: (Description menu not popping up)
Error

What I get:
image
What I expect to get:
image

As a little repro as to the GIF above in a much simpler environment, you can see the attached place file and gif:
ErrorRepro.rbxl (22.0 KB)
Error2

5 Likes
#48

I’ve not had issues with using Mouse detection events on UIObjects for a long time, so I was surprised to see this was happening again. However, using your repro, I added colour indicators to the frames which appears to be displaying as expected, but the indicator frame doesn’t turn visible.

#49

Same problem here…
It seems Roblox script is not respecting the MouseEnter and MouseLeave correct order, when the mouse moves fast.
I put a print with a counter and the name of the instance inside both MouseEnter and MouseLeave.
That’s what I got when the mouse moves slowly between two instances:

  1 -> Enter ImageButton1
  2 -> **** Leave ImageButton1
  3 -> Enter ImageButton2
  4 -> **** Leave ImageButton2

But then, if I move faster from ImageButton1 to ImageButton2:

  5 -> Enter ImageButton1
  6 -> Enter ImageButton2
  7 -> **** Leave ImageButton1
  8 -> **** Leave ImageButton2

As you can see MouseEnter from ImageButton2 is being fired BEFORE MouseLeave ImageButton1 …

So, the question is: how to avoid Roblox to run in this Assyncronous way?

#50

I think I solved the problem:

Just insert a wait() at the very beginning of MouseEnter event. :point_left:

This will avoid that asynchrony problem.

3 Likes
#51

I would recommend waiting a frame using e.g. RenderStepped rather than wait(). With wait() you get typically a 2 frame wait, and it is not guaranteed to resume at the earliest possible moment due to potential throttling. Signals like RenderStepped/Heartbeat/Stepped are guaranteed to run every frame, and are never deferred to the next frame.

5 Likes
#53

Putting a renderstepped wait fixed the problem, but we really shouldn’t have to do this.

9 Likes
#55

image


#56

yep. had this same issue in Tween MouseLeave not playing unless MouseEnter tween is finished

#57

I am still experiencing this issue to this day, but only with CoreGui, if an engineer is reading this, please fix the issue with CoreGui

Here’s a video of the problem:

robloxapp-20220303-1725267.wmv (83.5 KB)

#58

No clue how this is still a prominent issue four years later in 2022. I’ve been using a custom implementation because of this for the last few years (when I shouldn’t even have to), and I decided to try it out again to see if it got fixed during that time, but it still fails to run in order.

SHAREX_1647954605

It runs the next button’s Enter before it runs the current button’s Leave. MouseLeave actually fires out of order.

image

4 Likes
#59

It mainly happens on mobile, does it happen on PC too?

#60

I also have this problem when working with hovering UIs. My way around this is to use PlayerGui:GetGuiObjectsAtPosition(x, y), with the x and y arguments being the mouse position. It’s a hacky method, but it seems to work for me.

4 Likes
#64

Hello! We are following up to see if this bug is still affecting devs as we are having some trouble reproducing this issue.

If this issue is still affecting you, please reply back with details and a test place if possible. Thank you!

#65

Not entirely sure but it seems like it has been fixed? IIRC the last few times I’ve been using this event it has been working fine regardless of mouse speed

#66

Hmmm :thinking: just came across this post and can’t help but wonder, is this still planned? Does TweenService offer any extra benefit over using these alternative methods?