Description of problem:
Drag and drop a .desktop file to the menu editor

Version-Release number of selected component:
mozo-1.22.1-1.fc29

Additional info:
reporter:       libreport-2.10.0
cmdline:        /usr/bin/python3 -OOt /usr/bin/mozo
crash_function: on_item_tree_drag_data_received
exception_type: AttributeError
executable:     /usr/bin/mozo
interpreter:    python3-3.7.3-1.fc29.x86_64
kernel:         5.0.13-200.fc29.x86_64
runlevel:       N 5
type:           Python3
uid:            1000

Truncated backtrace:
MainWindow.py:546:on_item_tree_drag_data_received:AttributeError: 'SelectionData' object has no attribute 'data'

Traceback (most recent call last):
  File "/usr/lib/python3.7/site-packages/Mozo/MainWindow.py", line 546, in on_item_tree_drag_data_received
    if selection.data is None:
AttributeError: 'SelectionData' object has no attribute 'data'

Local variables in innermost frame:
self: <Mozo.MainWindow.MainWindow object at 0x7fa24d5e55f8>
treeview: <Gtk.TreeView object at 0x7fa24901ee10 (GtkTreeView at 0x55560bc867c0)>
context: <GdkX11.X11DragContext object at 0x7fa24901eee8 (GdkX11DragContext at 0x55560bd92bb0)>
x: 229
y: 206
selection: <Gtk.SelectionData object at 0x7fa24b04fa68 (GtkSelectionData at 0x7ffc41729610)>
info: 1
etime: 119001214
items: <Gtk.ListStore object at 0x7fa24b5f79d8 (GtkListStore at 0x55560bee3560)>
types_before: (<enum GTK_TREE_VIEW_DROP_BEFORE of type Gtk.TreeViewDropPosition>, <enum GTK_TREE_VIEW_DROP_INTO_OR_BEFORE of type Gtk.TreeViewDropPosition>)
types_into: (<enum GTK_TREE_VIEW_DROP_INTO_OR_BEFORE of type Gtk.TreeViewDropPosition>, <enum GTK_TREE_VIEW_DROP_INTO_OR_AFTER of type Gtk.TreeViewDropPosition>)
types_after: (<enum GTK_TREE_VIEW_DROP_AFTER of type Gtk.TreeViewDropPosition>, <enum GTK_TREE_VIEW_DROP_INTO_OR_AFTER of type Gtk.TreeViewDropPosition>)