Tuomo confirmed that the change to using the icon window's class name was a bug.
ion3 (20080103-1) unstable; urgency=low
* New upstream version
+ * Fixed upstream regression which lost dockapp class names
+ (105_dockapp-class-from-hint-window.diff)
+ * Disabled dockapp size kludge for Docker (213_unkludge-docker.diff)
- -- Ben Hutchings <ben@decadent.org.uk> Sun, 06 Jan 2008 01:43:32 +0000
+ --
ion3 (20071109-1) unstable; urgency=low
--- /dev/null
+--- ion3.orig/ioncore/clientwin.c
++++ ion3/ioncore/clientwin.c
+@@ -509,13 +509,13 @@
+ xwindow_unmanaged_selectinput(win, 0);
+ xwindow_unmanaged_selectinput(icon_win, StructureNotifyMask);
+
+- win=icon_win;
+- attr=icon_attr;
+-
+ /* Copy WM_CLASS as _ION_DOCKAPP_HACK */
+
+ p=xwindow_get_text_property(win, XA_WM_CLASS, &n);
+
++ win=icon_win;
++ attr=icon_attr;
++
+ if(p!=NULL){
+ xwindow_set_text_property(icon_win, ioncore_g.atom_dockapp_hack,
+ (const char **)p, n);
--- /dev/null
+--- ion3.orig/etc/cfg_kludges.lua
++++ ion3/etc/cfg_kludges.lua
+@@ -26,6 +26,13 @@
+ min_size = { w = 64, h = 64},
+ }
+
++-- Make an exception for Docker, which sets correct size hints.
++defwinprop{
++ is_dockapp = true,
++ class = "Docker",
++ statusbar = "systray",
++}
++
+
+ -- You might want to enable these if you really must use XMMS.
+ --[[
+105_dockapp-class-from-hint-window.diff
201_build-config.diff
205_ion-lock.diff
206_use-x-terminal-emulator.diff
210_use-cfg_debian_ext.diff
211_add-debian-menu.diff
212_suggest-ion3-doc.diff
+213_unkludge-docker.diff