gtk: Add show_tabs=on|off command line option.

The patch adds "show_tabs" command line option for GTK ui similar to
"grab_on_hover". This option allows tabbed view mode to not have to be
enabled by hand at each start of the VM.

Signed-off-by: Felix "xq" Queißner <xq@random-projects.net>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220712133753.18937-1-xq@random-projects.net>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
diff --git a/qemu-options.hx b/qemu-options.hx
index 377d22f..79e0091 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1938,7 +1938,7 @@
 #endif
 #if defined(CONFIG_GTK)
     "-display gtk[,full-screen=on|off][,gl=on|off][,grab-on-hover=on|off]\n"
-    "            [,show-cursor=on|off][,window-close=on|off]\n"
+    "            [,show-tabs=on|off][,show-cursor=on|off][,window-close=on|off]\n"
 #endif
 #if defined(CONFIG_VNC)
     "-display vnc=<display>[,<optargs>]\n"
@@ -2023,6 +2023,10 @@
 
         ``grab-on-hover=on|off`` : Grab keyboard input on mouse hover
 
+        ``show-tabs=on|off`` : Display the tab bar for switching between the
+                               various graphical interfaces (e.g. VGA and
+                               virtual console character devices) by default.
+
         ``show-cursor=on|off`` :  Force showing the mouse cursor
 
         ``window-close=on|off`` : Allow to quit qemu with window close button