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  1. Qt
  2. QTBUG-75118

Tooltips lead to UI lock-ups/hangs



    • Bug
    • Status: Closed
    • P2: Important
    • Resolution: Out of scope
    • 5.11
    • None
    • None
    • Windows 10, x64 app, compiled with vs2015
    • Windows


      I ran into a weird issue where tooltips on some QPushButtons seems to cause quite extreme UI hangs / lock-ups when rendering the tooltip.

      This in the context of heavy CPU load on the system (e.g. 24 render threads running on a 12 core system), regardless the UI lock-up is pretty extreme (e..g up to 30s)

      Steps to replicate


      1) Download and Install Chaotica 2.0.10 (http://www.chaoticafractals.com/dist/chaotica_x64_v2.0.10.msi)

      2) Run Chaotica 2.0.10

      3) A window called the 'Parameter Browser' will pop up, click on the top-left thumbnail button.

      (This will start a render going in the main window)

      4) Move your mouse cursor to another thumbnail, then leave it still to allow a tooltip to pop up

      5) Result: Chaotica UI will lock up for 10-30s.

      If this doesn't happen immediately you may need to repeat steps 3 to 5 until it does.

      You can open the Parameter Browser window again with CTRL+B in the main window.


      The evidence for tooltips being the problem is that the UI locks up exactly when a tooltip would render, and the issue has been worked around by removing the tooltips.



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            lagocs Laszlo Agocs
            NChapman Nicholas Chapman
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