gtk: hook up to meson build
diff --git a/ext/gtk/meson.build b/ext/gtk/meson.build
index 324bfba..d7aeee2 100644
--- a/ext/gtk/meson.build
+++ b/ext/gtk/meson.build
@@ -43,7 +43,7 @@
 
   gstgtk = library('gstgtk',
     gtk_sources,
-    c_args : gst_plugins_bad_args + gtk_defines,
+    c_args : gst_plugins_good_args + gtk_defines,
     link_args : noseh_link_args,
     include_directories : [configinc],
     dependencies : [gtk_dep, gstvideo_dep, gstbase_dep, libm] + optional_deps,
diff --git a/ext/meson.build b/ext/meson.build
index 2758877..d5eb382 100644
--- a/ext/meson.build
+++ b/ext/meson.build
@@ -2,6 +2,7 @@
 subdir('cairo')
 subdir('flac')
 subdir('gdk_pixbuf')
+subdir('gtk')
 subdir('jack')
 subdir('jpeg')
 subdir('lame')
diff --git a/meson.build b/meson.build
index d4f05aa..8149ec3 100644
--- a/meson.build
+++ b/meson.build
@@ -194,6 +194,41 @@
 gstvideo_dep = dependency('gstreamer-video-1.0', version : gst_req,
     fallback : ['gst-plugins-base', 'video_dep'])
 
+# GStreamer OpenGL
+gstgl_dep = dependency('gstreamer-gl-1.0', version : gst_req,
+    fallback : ['gst-plugins-base', 'gstgl_dep'], required: false)
+
+build_gstgl = gstgl_dep.found() # FIXME: add option?
+
+if build_gstgl
+  if gstgl_dep.type_name() == 'pkgconfig'
+    gst_gl_apis = gstgl_dep.get_pkgconfig_variable('gl_apis').split()
+    gst_gl_winsys = gstgl_dep.get_pkgconfig_variable('gl_winsys').split()
+    gst_gl_platforms = gstgl_dep.get_pkgconfig_variable('gl_platforms').split()
+  else
+    gstbase = subproject('gst-plugins-base')
+    gst_gl_apis = gstbase.get_variable('enabled_gl_apis')
+    gst_gl_winsys = gstbase.get_variable('enabled_gl_winsys')
+    gst_gl_platforms = gstbase.get_variable('enabled_gl_platforms')
+  endif
+
+  message('GStreamer OpenGL window systems: @0@'.format(' '.join(gst_gl_winsys)))
+  message('GStreamer OpenGL platforms: @0@'.format(' '.join(gst_gl_platforms)))
+  message('GStreamer OpenGL apis: @0@'.format(' '.join(gst_gl_apis)))
+
+  foreach ws : ['x11', 'wayland', 'android', 'cocoa', 'eagl', 'win32', 'dispmanx', 'viv_fb']
+    set_variable('gst_gl_have_window_@0@'.format(ws), gst_gl_winsys.contains(ws))
+  endforeach
+
+  foreach p : ['glx', 'egl', 'cgl', 'eagl', 'wgl']
+    set_variable('gst_gl_have_platform_@0@'.format(p), gst_gl_platforms.contains(p))
+  endforeach
+
+  foreach api : ['opengl', 'gles2']
+    set_variable('gst_gl_have_api_@0@'.format(api), gst_gl_apis.contains(api))
+  endforeach
+endif
+
 zlib_dep = dependency('zlib', required : false)
 bz2lib = cc.find_library('bz2', required : false)
 glib_deps = [dependency('glib-2.0', version : glib_req, fallback: ['glib', 'libglib_dep']),
diff --git a/tests/examples/meson.build b/tests/examples/meson.build
index bf70134..3c66c55 100644
--- a/tests/examples/meson.build
+++ b/tests/examples/meson.build
@@ -1,5 +1,6 @@
 subdir('audiofx')
 subdir('cairo')
+#FIXME: subdir('gtk')
 subdir('level')
 subdir('rtp')
 subdir('shapewipe')