userguide: Mention know issues for assign (#3434)

[i3/i3] / docs / userguide

diff --git a/docs/userguide b/docs/userguide
index 9c601e8869167da2385665ba66a1d57e782393f6..da5d98737197ca0fb9cd1416bf287068df69768c 100644 (file)
--- a/docs/userguide
+++ b/docs/userguide
@@ -755,14 +755,23 @@ set_from_resource $black i3wm.color0 #000000
 
 To automatically make a specific window show up on a specific workspace, you
 can use an *assignment*. You can match windows by using any criteria,
-see <<command_criteria>>. It is recommended that you match on window classes
-(and instances, when appropriate) instead of window titles whenever possible
-because some applications first create their window, and then worry about
-setting the correct title. Firefox with Vimperator comes to mind. The window
-starts up being named Firefox, and only when Vimperator is loaded does the
-title change. As i3 will get the title as soon as the application maps the
-window (mapping means actually displaying it on the screen), you’d need to have
-to match on 'Firefox' in this case.
+see <<command_criteria>>. The difference between +assign+ and
++for_window <criteria> move to workspace+ is that the former will only be
+executed when the application maps the window (mapping means actually displaying
+it on the screen) but the latter will be executed whenever a window changes its
+properties to something that matches the specified criteria.
+
+Thus, it is recommended that you match on window classes (and instances, when
+appropriate) instead of window titles whenever possible because some
+applications first create their window, and then worry about setting the correct
+title. Firefox with Vimperator comes to mind. The window starts up being named
+Firefox, and only when Vimperator is loaded does the title change. As i3 will
+get the title as soon as the application maps the window, you’d need to have to
+match on 'Firefox' in this case.
+Another known issue is with Spotify, which doesn't set the class hints when
+mapping the window, meaning you'll have to use a +for_window+ rule to assign
+Spotify to a specific workspace.
+Finally, using +assign [tiling]+ and +assign [floating]+ is not supported.
 
 You can also assign a window to show up on a specific output. You can use RandR
 names such as +VGA1+ or names relative to the output with the currently focused