Uploaded image for project: 'Qt'
  1. Qt
  2. QTBUG-66111

Update of QWidget fails sporadically (X11)

    XMLWordPrintable

    Details

    • Type: Bug
    • Status: Closed
    • Priority: P2: Important
    • Resolution: Done
    • Affects Version/s: 5.10.0
    • Fix Version/s: 6.0
    • Component/s: QPA: X11/XCB
    • Labels:
      None
    • Environment:
      Qt 5.10.0, openSUSE Leap 42.3, KDE, g++ (SUSE Linux) 4.8.5, Intel Core I5-4460 CPU with integrated graphics controller

      Description

      The update of QWidget fails sporadically, apparently if a paint event follows a resize() call. The painted widget remains at first black, the missing contents appear e.g. when the mouse is moved to a another application's window and that window gets the focus. Possibly the backing store is not flushed properly. The described error does not occur, if the resize call does not really change the size (i.e. the new size equals the old).

      To reproduce the bug, extract the attached "qtbug.zip" and compile the contained application "app". The application shows a main window with a vertical scroll bar. Move the slider with different speeds up and down. While the slider is pressed, the application shows a small window with the slider position next to the slider. The size of this window is adapted to the currently needed space. The bug: Sporadically this window remains black.

      In the application's tool bar you find three buttons:

      • Random: If pressed, the application shows a random number instead of the slider position. Thus the number of resize operations and the likeliness to reproduce the error is raised.
      • Fixed: If pressed, the small window has a fixed size. In that case the error seems never to happen.
      • Hold: If pressed, the small window is not hidden, when the slider is released. Move the slider, until the small window remains black, then release the slider. Move the mouse across the desktop e.g. to a command tool. The missing number in the small window appears now.

       

        Attachments

          Issue Links

          No reviews matched the request. Check your Options in the drop-down menu of this sections header.

            Activity

              People

              Assignee:
              paeglis Gatis Paeglis
              Reporter:
              wschenke Winfried Schenke
              PM Owner:
              Veli-Pekka Heinonen Veli-Pekka Heinonen
              Votes:
              0 Vote for this issue
              Watchers:
              4 Start watching this issue

                Dates

                Created:
                Updated:
                Resolved:

                  Gerrit Reviews

                  There are no open Gerrit changes