added file chooser UI, changed the gtk.TargetEntry on D&D to uri-list and put all UI init in one function..

dropship.glade

@@ -2,6 +2,42 @@
 <!-- Generated with glade 3.36.0 -->
 <interface>
   <requires lib="gtk+" version="3.20"/>
+  <object class="GtkFileChooserDialog" id="filePicker">
+    <property name="can_focus">False</property>
+    <property name="title" translatable="yes">Choose files to ship</property>
+    <property name="type_hint">dialog</property>
+    <property name="select_multiple">True</property>
+    <child internal-child="vbox">
+      <object class="GtkBox">
+        <property name="can_focus">False</property>
+        <property name="orientation">vertical</property>
+        <property name="spacing">2</property>
+        <child internal-child="action_area">
+          <object class="GtkButtonBox">
+            <property name="can_focus">False</property>
+            <property name="layout_style">end</property>
+            <child>
+              <placeholder/>
+            </child>
+            <child>
+              <placeholder/>
+            </child>
+          </object>
+          <packing>
+            <property name="expand">False</property>
+            <property name="fill">False</property>
+            <property name="position">0</property>
+          </packing>
+        </child>
+        <child>
+          <placeholder/>
+        </child>
+      </object>
+    </child>
+    <child type="titlebar">
+      <placeholder/>
+    </child>
+  </object>
   <object class="GtkApplicationWindow" id="mainWindow">
     <property name="can_focus">False</property>
     <property name="resizable">False</property>
@@ -12,11 +48,12 @@
         <property name="visible">True</property>
         <property name="can_focus">False</property>
         <child>
-          <object class="GtkEventBox">
+          <object class="GtkEventBox" id="dropBox">
             <property name="visible">True</property>
             <property name="can_focus">False</property>
+            <signal name="button-press-event" handler="add_files" swapped="no"/>
             <child>
-              <object class="GtkBox" id="dropBox">
+              <object class="GtkBox">
                 <property name="visible">True</property>
                 <property name="can_focus">False</property>
                 <property name="margin_left">16</property>

dropship.py

@@ -50,8 +50,7 @@ class DropShip:
 
         self.init_glade()
         self.init_css()
-        self.init_drop_box()
-        self.init_recv_box()
+        self.init_ui_elements()
         self.init_window()
 
     def init_glade(self):
@@ -70,39 +69,42 @@ class DropShip:
         )
 
     def init_window(self):
-        """Initialise the GUI window."""
+        """Initialise the Main GUI window."""
         self.main_window_id = "mainWindow"
         self.window = self.builder.get_object(self.main_window_id)
         self.window.connect("delete-event", self.on_quit)
         self.window.show()
 
-    def init_drop_box(self):
-        """Initialise the drag & drop box."""
-        self.files_to_send = ""
-
-        # TODO(rra): check the target flags
-        # https://lazka.github.io/pgi-docs/Gtk-3.0/flags.html#Gtk.TargetFlags
-        self.enforce_target = gtk.TargetEntry.new("text/plain", gtk.TargetFlags(4), 129)
+    def init_ui_elements(self):
+        """Initialize the UI elements."""
 
-        self.drop_box_id = "dropBox"
-        self.drop_box_label = "dropLabel"
+        # Send UI
+        # Drag & Drop Box
+        self.files_to_send = ""
+        self.enforce_target = gtk.TargetEntry.new("text/uri-list", gtk.TargetFlags(4), 129)
 
-        self.drop_box = self.builder.get_object(self.drop_box_id)
+        self.drop_box = self.builder.get_object('dropBox')
         self.drop_box.drag_dest_set(
             gtk.DestDefaults.ALL, [self.enforce_target], gdk.DragAction.COPY
         )
         self.drop_box.connect("drag-data-received", self.on_drop)
-        self.drop_label = self.builder.get_object(self.drop_box_label)
+        self.drop_label = self.builder.get_object('dropLabel')
 
-    def init_recv_box(self):
-        """Initialise the receive code box."""
-        self.recv_box_id = "receiveBoxCodeEntry"
-        self.recv_box = self.builder.get_object(self.recv_box_id)
+        # File chooser
+        self.file_chooser = self.builder.get_object('filePicker')
+        self.file_chooser.add_buttons(
+            'Cancel', gtk.ResponseType.CANCEL, "Add", gtk.ResponseType.OK
+        )
+ 
+        # Receive UI
+        # Code entry box
+        self.recv_box = self.builder.get_object('receiveBoxCodeEntry')
         self.recv_box.connect("activate", self.on_recv)
 
+
     def on_drop(self, widget, drag_context, x, y, data, info, time):
         """Handler for file dropping."""
-        files = data.get_text().split()
+        files = data.get_uris()
         self.files_to_send = files
         if len(files) == 1:
             fpath = Path(files[0].replace("file://", ""))
@@ -111,6 +113,16 @@ class DropShip:
         else:
             log.info("Multiple file sending coming soon ™")
 
+    def add_files(self,widget, event):
+        """Handler for adding files with system interface"""
+        response = self.file_chooser.run()
+        if response == gtk.ResponseType.OK:
+            self.schedule(self.wormhole_send(self, self.file_chooser.get_filenames()[0]))
+        elif response == gtk.ResponseType.CANCEL:
+            #TODO(roel) something isn't right here.. maybe we need to initialize it every time we run it.
+            print("Cancel clicked")
+        self.file_chooser.destroy()
+
     def on_recv(self, entry):
         """Handler for receiving transfers."""
         code = entry.get_text()