When a user double-clicks, UE doesn't receive the second release

[DenisTensorWorks]

UE Version:
E.g. UE 5.2.1

Problem component
Frontend

Summary

In 5.2.1, when a user double-clicks, the second release is never received by UE. A user reports having to work around this by sending a release input action manually when their frontend detects a double click.

Description from the user

Input in the Pixel Streaming Demo example project works just fine. It uses the same input logic we use in our project to toggle camera pan (hold LMB to pan camera).

In our project, we also handle doubleclick natively (LMB bound to IE_DoubleClick) to select where our character is supposed to move. When we use the vanilla 5.2 pixel streaming infra, this is what happens:

1. We double click to move our character.
2. Our character moves, but camera panning is enabled afterwards without any buttons being held

Our team has discovered that this issue goes away after commenting out the body of this function.

What we ended up doing as a workaround is our frontend sends a mouse up event a short time after the double click event. This fixes the issue of our camera getting stuck at panning after double click.

We can probably use the top down project to repro this, it has click to move controls out of the box I believe.

Expected behavior
UE should be able to correctly handle double-clicks and register release events

Environment:

• Frontend: 5.2
• OS: (TBC)
• Browser: Chrome and Firefox

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Moved from EpicGames/PixelStreamingInfrastructure#359