Fall back to default dimensions if layout is unconfigured

plasma/layout.py

@@ -27,11 +27,14 @@ class Plasma(Layout):
         ('border_width_single', 0, 'Border width for single window'),
         ('margin', 0, 'Layout margin'),
     ]
+    # If windows are added before configure() was called, the screen size is
+    # still unknown, so we need to set some arbitrary initial root dimensions
+    default_dimensions = (0, 0, 1000, 1000)
 
     def __init__(self, **config):
         Layout.__init__(self, **config)
         self.add_defaults(Plasma.defaults)
-        self.root = Node()
+        self.root = Node(None, *self.default_dimensions)
         self.focused = None
         self.add_mode = None
 
@@ -52,7 +55,7 @@ def info(self):
     def clone(self, group):
         clone = copy.copy(self)
         clone.group = group
-        clone.root = Node()
+        clone.root = Node(None, *self.default_dimensions)
         clone.focused = None
         clone.add_mode = None
         return clone

tests/test_layout.py

@@ -9,7 +9,7 @@
 # We borrow Qtile's testing framework. That's not elegant but the best option.
 sys.path.insert(0, str(Path(__file__).parents[1] / 'lib'))  # noqa: E402
 from qtile.libqtile import config
-from qtile.libqtile.layout.floating import Floating
+from qtile.libqtile.layout import Floating
 from qtile.test.conftest import no_xinerama, qtile, xephyr, xvfb  # noqa: F401
 from qtile.test.layouts.layout_utils import assertFocused
 
@@ -217,3 +217,11 @@ def test_recent(self, qtile):
         assertFocused(qtile, 'a')
         qtile.c.layout.recent()
         assertFocused(qtile, 'c')
+
+    def test_bug_10(self):
+        """Adding nodes when the correct root dimensions are still unknown
+        should not raise an error.
+        """
+        layout = Plasma()
+        layout.add(object())
+        layout.add(object())