ui: improved diplaying default icons

In some DEs, like Enlightenment, some builtins icons may be empty.
The icon is not Null, but there're no available sizes, and the
pixmap is empty.

For now we'll use SP_FileIcon as the default icon, which exists
in this scenario, but we should create a new default icon, and
distribute it with the GUI.

Author: gustavo-iniguez-goya

ui/opensnitch/utils/__init__.py

@@ -512,7 +512,13 @@ def new(widget, icon_name):
         icon = QtGui.QIcon.fromTheme(icon_name, QtGui.QIcon.fromTheme(icon_name + "-symbolic"))
         if icon.isNull():
             try:
-                return widget.style().standardIcon(getattr(QtWidgets.QStyle, Icons.defaults[icon_name]))
+                icon = widget.style().standardIcon(getattr(QtWidgets.QStyle, Icons.defaults[icon_name]))
+                # in some DEs, like Enlightenment, some builtins icons may be
+                # empty. The icon is not Null, but there're no available sizes,
+                # and the pixmap is empty.
+                # TODO: Create a default icon, and distribute it as resource.
+                if len(icon.availableSizes()) == 0:
+                    icon = widget.style().standardIcon(getattr(QtWidgets.QStyle, 'SP_FileIcon'))
             except Exception as e:
                 print("Qt standardIcon exception:", icon_name, ",", e)