Send optimized icon size

Lookup for the most common icon sizes and select one of them first. Then
revert to whatever available size which does not violate our maximum.

Unfortunately pre-SVG era icon designs for few legacy applications is
totally different per icon size. So sending the highest resolution is
not always desirable as it does not scale down well on low-DPI screens.

Practically this patch does not change anything for most programs
(compared to previous situation). Since the previous code started from
128x128 down to the lowest resolution.

Background on various icon sizes in different OS:
https://icons8.com/blog/articles/choosing-the-right-size-and-format-for-icons/

resolves: QubesOS/qubes-issues#10359

Author: alimirjamali

window-icon-updater/icon-sender

@@ -34,7 +34,18 @@ import time
 import xcffib
 from xcffib import xproto
 
-ICON_MAX_SIZE = 256
+ICON_MAX_SIZE = 1024
+# Chronological order of preferred icon sizes based on certified HW and defaults
+ICON_PREFERRED_SIZES = (
+    (128, 128),
+    (96, 96),
+    (64, 64),
+    (48, 48),
+    (256, 256),
+    (512, 512),
+    (32, 32),
+)
+
 IconPixmapHint = 0b1 << 2
 IconMaskHint = 0b1 << 5
 
@@ -247,7 +258,13 @@ class IconRetriever(object):
     def describe_icon(self, w):
         try:
             icons = self.get_icons(w)
-            chosen_size = sorted(icons.keys())[-1]
+            # Override the largest icon with our preferred sizes (if possible)
+            for size in ICON_PREFERRED_SIZES:
+                if size in icons.keys():
+                    chosen_size = size
+                    break
+            else:
+                chosen_size = sorted(icons.keys())[-1]
 
             data = b''
             data += "{}\n".format(w).encode('ascii')