SUMMARY When using the WA_PaintOnScreen attribute on a QMainWindow with Qt5, it is impossible to interactively resize the window under X11+Kwin. This does not happen with other window managers I tested (mutter, i3's, xfce's). STEPS TO REPRODUCE 1. Create a QMainWindow with the WA_PaintOnScreen attribute set 2. Try to manually resize the window under X11+Kwin A test repo is available here: https://github.com/nullgemm/QmlX11Composition.git Here is the line setting the attribute: https://github.com/nullgemm/QmlX11Composition/blob/master/RenderWindow.cpp#L64 OBSERVED RESULT The window does not resize. EXPECTED RESULT The window resizes. SOFTWARE/OS VERSIONS Linux Kernel Version: 5.11.12 Plasma Version: 5.21.4 Plasma Framework Version: 5.80.0 Qt Version: 5.15.2 ADDITIONAL INFORMATION The versions information above is that of my main setup but this issue could be reproduced on 2 other ones. Snapping the window on the side of the screen does resize it as expected.
Please include output of "xprop" on your window.
QT_ONSCREEN_PAINT=1 reproduces it. Debugged to confirm _NET_SYNC_REQUEST are not sent properly. I'm surprised this doesn't affect Mutter, but this doesn't look like a kwin bug until proved otherwise.
(In reply to David Edmundson from comment #1) > Please include output of "xprop" on your window. _NET_WM_ICON_GEOMETRY(CARDINAL) = 191, 1060, 28, 20 _NET_WM_ALLOWED_ACTIONS(ATOM) = _NET_WM_ACTION_MOVE, _NET_WM_ACTION_RESIZE, _NET_WM_ACTION_MINIMIZE, _NET_WM_ACTION_SHADE, _NET_WM_ACTION_MAXIMIZE_VERT, _NET_WM_ACTION_MAXIMIZE_HORZ, _NET_WM_ACTION_FULLSCREEN, _NET_WM_ACTION_CHANGE_DESKTOP, _NET_WM_ACTION_CLOSE _KDE_NET_WM_FRAME_STRUT(CARDINAL) = 0, 0, 29, 0 _NET_FRAME_EXTENTS(CARDINAL) = 0, 0, 29, 0 _NET_WM_DESKTOP(CARDINAL) = 0 _KDE_NET_WM_ACTIVITIES(STRING) = "52da254f-5261-4dcb-9594-ff67b64dbea5" WM_STATE(WM_STATE): window state: Normal icon window: 0x0 _NET_WM_STATE(ATOM) = _NET_WM_ICON_NAME(UTF8_STRING) = XdndAware(ATOM) = BITMAP WM_NAME(STRING) = _NET_WM_NAME(UTF8_STRING) = "myprog" _KDE_NET_WM_USER_CREATION_TIME(CARDINAL) = 5213713 _MOTIF_WM_HINTS(_MOTIF_WM_HINTS) = 0x3, 0x3e, 0x7e, 0x0, 0x0 _NET_WM_WINDOW_TYPE(ATOM) = _NET_WM_WINDOW_TYPE_NORMAL _XEMBED_INFO(_XEMBED_INFO) = 0x0, 0x1 WM_CLIENT_LEADER(WINDOW): window id # 0x3400008 WM_HINTS(WM_HINTS): Client accepts input or input focus: True window id # of group leader: 0x3400008 WM_CLIENT_MACHINE(STRING) = "au486" _NET_WM_PID(CARDINAL) = 2753172 _NET_WM_SYNC_REQUEST_COUNTER(CARDINAL) = 54525959 WM_CLASS(STRING) = "myprog", "myprog" WM_PROTOCOLS(ATOM): protocols WM_DELETE_WINDOW, WM_TAKE_FOCUS, _NET_WM_PING, _NET_WM_SYNC_REQUEST WM_NORMAL_HINTS(WM_SIZE_HINTS): user specified size: 200 by 100 window gravity: Static