SDL_x11events.c: properly handle input focus events (fix bug #5426)

From maxi@daemonizer.de: Since some time I stated to observe an annoying bug with the forward movement suddenly stopping while I was still pressing the corresponding key for the forward movement. Releasing and pressing the key again continued the movement. I observed this in the game "Unreal Tournament 2004", but other software is probably also affected. The stop basically happens after a few minutues of pressing the key, though the time needed to reproduce the issue is not constant. While investigating the issue I found it started with a commit [1] in the Xorg xserver. Digging deeper into the code I found two commits [2] [3] in libsdl2 which looked like they would also fix the issue in libsdl1.2. I backported these two commits to the libsdl1.2 in Debian and can confirm that the bug got fixed by this. [1] https://cgit.freedesktop.org/xorg/xserver/commit/?id=c67f2eac56518163981af59f5accb7c79bc00f6a [2] https://hg.libsdl.org/SDL/rev/a1c4c17410e8 [3] https://hg.libsdl.org/SDL/rev/764129077d18
libsdl-org · Dec 30, 2020 · 74c08c5 · 74c08c5
1 parent f3bc60c
commit 74c08c5
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diff --git a/WhatsNew b/WhatsNew
@@ -52,6 +52,7 @@ Changes include:
 - X11video: fix SDL_VIDEORESIZE events not received when resizing
   window from the corner (inverted logic in X11 ConfigureNotify, i.e.
   resize handling - bug 1430.)
+- X11video: properly handle input focus events (bug 5426.)
 - X11video: unblock SDL_WM_GrabInput() GrabNotViewable case (bug 1155.)
 - Mac OS X: fix macOS 10.14 (Mojave) opengl issues (bug 4788.)
 - Mac OS X: fix crash on any input in Quartz code (bug 2560.)

diff --git a/docs.html b/docs.html
@@ -120,6 +120,9 @@ <H2> SDL 1.2.16 Release Notes </H2>
   window from the corner (inverted logic in X11 ConfigureNotify, i.e.
   resize handling - bug <a href="https://bugzilla.libsdl.org/show_bug.cgi?id=1430">1430</a>.)
 </P>
+<P>
+  X11video: properly handle input focus events (bug <a href="https://bugzilla.libsdl.org/show_bug.cgi?id=5426">5426</a>.)
+</P>
 <P>
   X11video: unblock SDL_WM_GrabInput() GrabNotViewable case (bug <a href="https://bugzilla.libsdl.org/show_bug.cgi?id=1155">1155</a>.)
 </P>

diff --git a/src/video/x11/SDL_x11events.c b/src/video/x11/SDL_x11events.c
@@ -485,6 +485,13 @@ printf("Mode: NotifyUngrab\n");
 
 	    /* Gaining input focus? */
 	    case FocusIn: {
+	    if (xevent.xfocus.mode == NotifyGrab || xevent.xfocus.mode == NotifyUngrab) {
+		/* Someone is handling a global hotkey, ignore it */
+#ifdef DEBUG_XEVENTS
+		printf("FocusIn (NotifyGrab/NotifyUngrab, ignoring)\n");
+#endif
+		break;
+	    }
 #ifdef DEBUG_XEVENTS
 printf("FocusIn!\n");
 #endif
@@ -503,6 +510,13 @@ printf("FocusIn!\n");
 
 	    /* Losing input focus? */
 	    case FocusOut: {
+	    if (xevent.xfocus.mode == NotifyGrab || xevent.xfocus.mode == NotifyUngrab) {
+		/* Someone is handling a global hotkey, ignore it */
+#ifdef DEBUG_XEVENTS
+		printf("FocusOut (NotifyGrab/NotifyUngrab, ignoring)\n");
+#endif
+		break;
+	    }
 #ifdef DEBUG_XEVENTS
 printf("FocusOut!\n");
 #endif