gtk: Allow to activate grab-on-hover from the command line

As long as we have no persistent GTK configuration, this allows to
enable the useful grab-on-hover feature already when starting the VM.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

[ kraxel: fix warning with CONFIG_GTK=n ]

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
diff --git a/vl.c b/vl.c
index 842e897..1feb0ff 100644
--- a/vl.c
+++ b/vl.c
@@ -143,6 +143,9 @@
 static int full_screen = 0;
 static int no_frame = 0;
 int no_quit = 0;
+#ifdef CONFIG_GTK
+static bool grab_on_hover;
+#endif
 CharDriverState *serial_hds[MAX_SERIAL_PORTS];
 CharDriverState *parallel_hds[MAX_PARALLEL_PORTS];
 CharDriverState *virtcon_hds[MAX_VIRTIO_CONSOLES];
@@ -2276,6 +2279,25 @@
     } else if (strstart(p, "gtk", &opts)) {
 #ifdef CONFIG_GTK
         display = DT_GTK;
+        while (*opts) {
+            const char *nextopt;
+
+            if (strstart(opts, ",grab_on_hover=", &nextopt)) {
+                opts = nextopt;
+                if (strstart(opts, "on", &nextopt)) {
+                    grab_on_hover = true;
+                } else if (strstart(opts, "off", &nextopt)) {
+                    grab_on_hover = false;
+                } else {
+                    goto invalid_gtk_args;
+                }
+            } else {
+            invalid_gtk_args:
+                fprintf(stderr, "Invalid GTK option string: %s\n", p);
+                exit(1);
+            }
+            opts = nextopt;
+        }
 #else
         fprintf(stderr, "GTK support is disabled\n");
         exit(1);
@@ -4399,7 +4421,7 @@
 #endif
 #if defined(CONFIG_GTK)
     case DT_GTK:
-        gtk_display_init(ds, full_screen);
+        gtk_display_init(ds, full_screen, grab_on_hover);
         break;
 #endif
     default: