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  1. Qt
  2. QTBUG-99304

Scrolling with a touchpad on Windows is very laggy



    • Windows


      To reproduce, try creating a flickable containing a large scene, for example 8000 small rectangles. (you don't need this many to see a noticeable difference, however), and try scrolling using a touchpad

      As you can see in the video, in the exact same scene, scrolling with my laptop's touchscreen works perfectly smoothly, but scrolling with a touchpad causes huge amounts of lag and erratic/jerky scrolling

      When I sent a demo of my app to a friend (without the dots at the end, i added that in to make the bug more visible for the video), they were very annoyed by this bug too, they noticed that scrolling with their touchpad was very laggy, but with their touchscreen it was perfectly fine.

      Update: I also tested it with a mouse: it happens when sending many scroll events to the app, for example when the wheel is spun very forcefully, or with one of those scroll wheels that can just freely spin, in which it doesn't scroll at all until the wheel stops, and then scrolls by a large amount.

      Update 2: To my surprise, it actually works perfectly fine on Linux with a touchpad or a mouse, specifically Zorin OS 12 (derived from ubuntu)

      Update 3: Not sure if it's relevant to this, no idea if it's only a problem with linux, zorin, qt, or just my mouse, but after unplugging/replugging in my mouse in Linux/Zorin, my mouse scroll wheel stops functioning in my app only until the app is restarted, scrolling still works fine with other apps, doesn't seem to happen on windows either

      Update 4: The mouse scrolling problem in linux seems to have been fixed, was having this problem in QtCreator too, when i accidentally disconnected my mouse, which i did somewhat often, the scrolling would no longer work until i restarted the app, but recently this problem went away, i suppose in a new update.


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              qt.team.quick.subscriptions Qt Quick and Widgets Team
              jirauser62869 user-8aa0b (Inactive)
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