[gnome-boxes/add-tablet-only-if-supported] vm-configurator: Only add USB Tablet if supported

[Felipe Borges <felipeborges src gnome org>]

commit 836f3888746c668f37d51504011c7b5aed4381aa
Author: Felipe Borges <felipeborges gnome org>
Date:   Tue Dec 4 15:11:45 2018 +0100

    vm-configurator: Only add USB Tablet if supported
    
    We can rely on libosinfo to verify whether a given operating
    system supports a "tablet" device.
    
    Fixes #49

 src/vm-configurator.vala | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
---
diff --git a/src/vm-configurator.vala b/src/vm-configurator.vala
index 9e8e24ef..53e5c9fd 100644
--- a/src/vm-configurator.vala
+++ b/src/vm-configurator.vala
@@ -417,7 +417,10 @@ private static void set_sound_config (Domain domain, InstallerMedia install_medi
     }
 
     private static void set_tablet_config (Domain domain, InstallerMedia install_media) {
-        set_input_config (domain, DomainInputDeviceType.TABLET);
+        var device = find_device_by_prop (install_media.supported_devices, DEVICE_PROP_CLASS, "tablet");
+        if (device != null) {
+            set_input_config (domain, DomainInputDeviceType.TABLET);
+        }
     }
 
     private static void set_mouse_config (Domain domain, InstallerMedia install_media) {