adds vendor directory

vendors dependencies in standard `vendor` directory, managed by glide

vendor/github.com/mattn/go-gtk/example/dnd/dnd.go

@@ -0,0 +1,64 @@
+package main
+
+import (
+	"os"
+	"strings"
+	"unsafe"
+
+	"github.com/mattn/go-gtk/gdk"
+	"github.com/mattn/go-gtk/glib"
+	"github.com/mattn/go-gtk/gtk"
+)
+
+func main() {
+	gtk.Init(&os.Args)
+	window := gtk.NewWindow(gtk.WINDOW_TOPLEVEL)
+	window.SetTitle("GTK DND")
+	window.Connect("destroy", gtk.MainQuit)
+
+	vbox := gtk.NewVBox(true, 0)
+	vbox.SetBorderWidth(5)
+
+	targets := []gtk.TargetEntry{
+		{"text/uri-list", 0, 0},
+		{"STRING", 0, 1},
+		{"text/plain", 0, 2},
+	}
+	dest := gtk.NewLabel("drop me file")
+	dest.DragDestSet(
+		gtk.DEST_DEFAULT_MOTION|
+			gtk.DEST_DEFAULT_HIGHLIGHT|
+			gtk.DEST_DEFAULT_DROP,
+		targets,
+		gdk.ACTION_COPY)
+	dest.DragDestAddUriTargets()
+	dest.Connect("drag-data-received", func(ctx *glib.CallbackContext) {
+		sdata := gtk.NewSelectionDataFromNative(unsafe.Pointer(ctx.Args(3)))
+		if sdata != nil {
+			a := (*[2000]uint8)(sdata.GetData())
+			files := strings.Split(string(a[0:sdata.GetLength()-1]), "\n")
+			for i := range files {
+				filename, _, _ := glib.FilenameFromUri(files[i])
+				files[i] = filename
+			}
+			dialog := gtk.NewMessageDialog(
+				window,
+				gtk.DIALOG_MODAL,
+				gtk.MESSAGE_INFO,
+				gtk.BUTTONS_OK,
+				strings.Join(files, "\n"))
+			dialog.SetTitle("D&D")
+			dialog.Response(func() {
+				dialog.Destroy()
+			})
+			dialog.Run()
+		}
+	})
+	vbox.Add(dest)
+
+	window.Add(vbox)
+
+	window.SetSizeRequest(300, 100)
+	window.ShowAll()
+	gtk.Main()
+}