From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io1-xd2f.google.com (mail-io1-xd2f.google.com [IPv6:2607:f8b0:4864:20::d2f]) by sourceware.org (Postfix) with ESMTPS id 4FDDA3858405 for ; Sat, 30 Apr 2022 01:40:17 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 4FDDA3858405 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-io1-xd2f.google.com with SMTP id c125so11425799iof.9 for ; Fri, 29 Apr 2022 18:40:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to; bh=jE+74qzUuOrfH/mzDeL27415T/S0gy051L0Px3MdRpo=; b=XATRaveW+MIdYYX4lrY/D1B2mj7zujoLULuB2zLEuWvzdd5HIm2U+S3grQmQGQ48rD 0wG1/jBVALthB69eaEUoHze/es3lNXUbJuuYRGOgyNbTxiVHUTym6TURwPsXSV9Zh+j7 IlnptZCRX3w/OGSFzlMkfT6sxYUc736XjiJgGLR9+pjrcOfclq9rsXAuPRyhnQTIDk8E ydi0ysFrQwctQ285pWN68xTNqEWxLkWTyx3i+Bzip3ydco/Rf0QoOaUUxQxeOuOMbc+k 0HtgzZ1objbgvuVk2xZasxXvjCTvsS5MP1khdT6uDB6j3Y9BcKy7QlcfRGLDv2Q8audD Sz9w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to; bh=jE+74qzUuOrfH/mzDeL27415T/S0gy051L0Px3MdRpo=; b=b8810P3oY+5jXz1VaDXdyRvXeYBCgoO31/4m60HyanD++mDCGKrX8ONCjp1W5C+cZ0 JdVJqVnxtp3Bcz3ptmxOmb6Pru/V6OS9CReWk8dIrdONjwPk3Y3G9ndQqoX/09pSe2Ie pyyH2e8WzILkvCi7B0xg0XYcMq8WQjzfF3pb4ltOg4ifjKnXYOtybD/6hGSutAT0D3zZ 1Sk1kny6Jy15sFywKit5I0l1mZltYOIkZSTI2lQCbIBsXD/m1XUQz7hLCUqd8t9yGmJV YAAhQR1eP96v9DhFzpMAHCu1jxcUWPArB/HCimrGYTgwMpIA5vny5XtOvQffSKTYNdYK lbyA== X-Gm-Message-State: AOAM5331GrquF2RWcS5t71GP3qk2FjzHpiF1naLW/d+Bv3hSoP/+0zUM yLN0I+Y66tqS5fMK9zTGvv9elOWW0ZZO7PiHI68rCEhzee8= X-Google-Smtp-Source: ABdhPJz5lK8nAb2iOBMRouBhC265hpBYLJkXta/1QGOQy9q5RyUFeCW2N8l7wHzE8Br2jgWZPoVjURuhRGHWIiVKPs0= X-Received: by 2002:a05:6602:150f:b0:64c:6878:1ec8 with SMTP id g15-20020a056602150f00b0064c68781ec8mr821244iow.143.1651282816301; Fri, 29 Apr 2022 18:40:16 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: "S.J. Luo" Date: Sat, 30 Apr 2022 09:40:06 +0800 Message-ID: Subject: Re: Window flickering problem in XWin multiwindow mode To: cygwin@cygwin.com Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-0.3 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, KAM_ASCII_DIVIDERS, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=no autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: cygwin@cygwin.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: General Cygwin discussions and problem reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 30 Apr 2022 01:40:18 -0000 SL on Apr 26, 2022: > I have some EDA tools running on a Linux machine and display on my Windows > PC using xorg-server-21.1.3 XWin multiwindow mode > Sometimes the application window flickers forever for an unknown reason. > The problem became more severe after my PC upgrade to Windows10. > After re-compiling and debugging, I found a calling loop triggered. > Knowing the root cause, I am now able to demonstrate the issue with a small > test case as well as a patch that works for me. Both are attached below. Any one successfully duplicated the issue? I minor revised the test case so it won't silently go exit on wrong DISPLAY setting and added some comment. The running steps: gcc -o flicker2 flicker2.c -lX11 /usr/bin/XWin.exe :11 -ac -multiwindow & DISPLAY=:11 flicker2.exe On running, you would see a window switching rapidly between max and normal states and never stops. The key of triggering the window flickering(or flashing) are these two lines: SetWindowMax(display, win, _NET_WM_STATE_ADD); SetWindowMax(display, win, _NET_WM_STATE_REMOVE); where they just set the window to be maximized and go back to normal. Removing either of the two, the test case would become normal. I've tried this test case on 3PCs including Windows 7 and Windows 10 and in all cases the issue happens. This issue literally occurs on my work that runs some proprietary Linux EDA software. I wish this can be solved on next update. SL flicker2.c =================================================================== #include #include #include #include #define _NET_WM_STATE_REMOVE 0 #define _NET_WM_STATE_ADD 1 void SetWindowMax(Display *dpy, Window win, int state) { XEvent xev; Atom wm_state = XInternAtom(dpy, "_NET_WM_STATE", False); Atom max_horz = XInternAtom(dpy, "_NET_WM_STATE_MAXIMIZED_HORZ", False); Atom max_vert = XInternAtom(dpy, "_NET_WM_STATE_MAXIMIZED_VERT", False); memset(&xev, 0, sizeof(xev)); xev.type = ClientMessage; xev.xclient.window = win; xev.xclient.message_type = wm_state; xev.xclient.format = 32; xev.xclient.data.l[0] = state; xev.xclient.data.l[1] = max_horz; xev.xclient.data.l[2] = max_vert; XSendEvent(dpy, DefaultRootWindow(dpy), False, SubstructureNotifyMask, &xev); } int main(void) { Display *display; Window win; XEvent xev; int screen; if (!(display = XOpenDisplay(NULL))) { printf("Cannot open display. Please check DISPLAY environmet setting.\n"); exit(1); } screen = DefaultScreen(display); win = XCreateSimpleWindow(display, RootWindow(display, screen), 10, 10, 100, 100, 0, BlackPixel(display, screen), WhitePixel(display, screen)); XMapWindow(display, win); // Uncomment either of the following two lines // and window would not go flashing SetWindowMax(display, win, _NET_WM_STATE_ADD); SetWindowMax(display, win, _NET_WM_STATE_REMOVE); while(1) { XNextEvent(display, &xev); } // It is supposed never get here XCloseDisplay(display); return 0; } ===================================================================