Add Gtk.ProgressBar testcase.

Signed-off-by: Manuel Quiñones <manuq@laptop.org>

tests/graphics/progress.py

@@ -0,0 +1,20 @@
+from gi.repository import Gtk
+
+import common
+
+
+test = common.Test()
+test.show()
+
+box = Gtk.HBox()
+test.pack_start(box, True, False, 10)
+box.show()
+
+bar = Gtk.ProgressBar()
+bar.set_fraction(0.5)
+box.pack_start(bar, True, True, 10)
+bar.show()
+
+
+if __name__ == '__main__':
+    common.main(test)