ui: add option to specify use of explict tray icon files and their size

docs/index.md

@@ -121,8 +121,11 @@ for the step-by-step procedure for manual installation.
 - If some icons appear broken in the application, make sure you've properly
   configured the Gtk theme and icon theme in your control panel.
 
-- There are several implementations of the system tray.   Some of these have problems
-  that can result in missing or wrong-sized icons.
+- Solaar normally uses icon names for its icons, which in some system tray implementatations
+  results in missing or wrong-sized icons.
+  The `--tray-icon-size` option forces Solaar to use icon files of appropriate size
+  for tray icons instead, which produces better results in some system tray implementatations.
+  To use icon files close to 32 pixels in size use `--tray-icon-size=32`.
 
 - The icon in the system tray can show up as 'black on black' in dark
   themes or as non-symbolic when the theme uses symbolic icons.  This is due to problems

lib/solaar/gtk.py

@@ -81,6 +81,7 @@ def _parse_arguments():
         choices=('regular', 'symbolic', 'solaar'),
         help='prefer regular battery / symbolic battery / solaar icons'
     )
+    arg_parser.add_argument('--tray-icon-size', type=int, help='explicit size for tray icons')
     arg_parser.add_argument('-V', '--version', action='version', version='%(prog)s ' + __version__)
     arg_parser.add_argument('--help-actions', action='store_true', help='print help for the optional actions')
     arg_parser.add_argument('action', nargs=argparse.REMAINDER, choices=_cli.actions, help='optional actions to perform')
@@ -96,6 +97,8 @@ def _parse_arguments():
 
     global battery_icons_style
     battery_icons_style = args.battery_icons if args.battery_icons is not None else 'regular'
+    global tray_icon_size
+    tray_icon_size = args.tray_icon_size
 
     import logging
     if args.debug > 0:

lib/solaar/ui/tray.py

@@ -42,7 +42,7 @@ del getLogger
 # constants
 #
 
-_TRAY_ICON_SIZE = 64  # pixels - make large as downscaling is done but not always upscaling
+_TRAY_ICON_SIZE = 48
 _MENU_ICON_SIZE = Gtk.IconSize.LARGE_TOOLBAR
 _RECEIVER_SEPARATOR = ('~', None, None, None)
 
@@ -174,9 +174,11 @@ try:
     # https://bugs.launchpad.net/ubuntu/+source/libappindicator/+bug/1363277
     # Defense against bug that shows up in XFCE 4.16 where icons are not upscaled
     def _icon_file(icon_name):
-        if False and not os.path.isfile(icon_name):
+        if gtk.tray_icon_size is None and not os.path.isfile(icon_name):
             return icon_name
-        icon_info = Gtk.IconTheme.get_default().lookup_icon(icon_name, _TRAY_ICON_SIZE, Gtk.IconLookupFlags.FORCE_SVG)
+        icon_info = Gtk.IconTheme.get_default().lookup_icon(
+            icon_name, gtk.tray_icon_size or _TRAY_ICON_SIZE, Gtk.IconLookupFlags.FORCE_SVG
+        )
         return icon_info.get_filename() if icon_info else icon_name
 
     def _create(menu):