floating: Don't use fullscreen size as floating size

23 files changed, 135 insertions, 45 deletions

diff --git a/src/layout/floating.rs b/src/layout/floating.rs
index 58ef8427..6b997405 100644
--- a/src/layout/floating.rs
+++ b/src/layout/floating.rs
@@ -375,8 +375,9 @@ impl<W: LayoutElement> FloatingSpace<W> {
             floating_size.unwrap_or_default()
         } else {
             // If the window wasn't fullscreen without a floating size (e.g. it was tiled before),
-            // ask for the current size.
-            floating_size.unwrap_or_else(|| win.expected_size())
+            // ask for the current size. If the current size is unknown (the window was only ever
+            // fullscreen until now), fall back to (0, 0).
+            floating_size.unwrap_or_else(|| win.expected_size().unwrap_or_default())
         };
         // Make sure fixed-size through window rules keeps working.
         let min_size = win.min_size();
@@ -482,8 +483,10 @@ impl<W: LayoutElement> FloatingSpace<W> {
             }
         }
 
-        // Store the floating size.
-        tile.set_floating_window_size(tile.window().expected_size());
+        // Store the floating size if we have one.
+        if let Some(size) = tile.window().expected_size() {
+            tile.set_floating_window_size(size);
+        }
 
         let width = ColumnWidth::Fixed(tile.window_size().w);
         RemovedTile {
@@ -600,7 +603,7 @@ impl<W: LayoutElement> FloatingSpace<W> {
         win_width = ensure_min_max_size(win_width, min_size.w, max_size.w);
         win_width = max(1, win_width);
 
-        let win_height = win.expected_size().h;
+        let win_height = win.expected_size().unwrap_or_default().h;
         let win_height = ensure_min_max_size(win_height, min_size.h, max_size.h);
 
         let win_size = Size::from((win_width, win_height));
@@ -626,7 +629,7 @@ impl<W: LayoutElement> FloatingSpace<W> {
         win_height = ensure_min_max_size(win_height, min_size.h, max_size.h);
         win_height = max(1, win_height);
 
-        let win_width = win.expected_size().w;
+        let win_width = win.expected_size().unwrap_or_default().w;
         let win_width = ensure_min_max_size(win_width, min_size.w, max_size.w);
 
         let win_size = Size::from((win_width, win_height));
diff --git a/src/layout/mod.rs b/src/layout/mod.rs
index 74afa501..8bc137e0 100644
--- a/src/layout/mod.rs
+++ b/src/layout/mod.rs
@@ -197,7 +197,7 @@ pub trait LayoutElement {
     /// Size previously requested through [`LayoutElement::request_size()`].
     fn requested_size(&self) -> Option<Size<i32, Logical>>;
 
-    /// Size that we expect this window has or will shortly have.
+    /// Non-fullscreen size that we expect this window has or will shortly have.
     ///
     /// This can be different from [`requested_size()`](LayoutElement::requested_size()). For
     /// example, for floating windows this will generally return the current window size, rather
@@ -205,10 +205,15 @@ pub trait LayoutElement {
     /// size freely. But not always: if we just requested a floating window to resize and it hasn't
     /// responded to it yet, this will return the newly requested size.
     ///
-    /// This function should never return a 0 size component.
+    /// This function should never return a 0 size component. `None` means there's no known
+    /// expected size (for example, the window is fullscreen).
     ///
     /// The default impl is for testing only, it will not preserve the window's own size changes.
-    fn expected_size(&self) -> Size<i32, Logical> {
+    fn expected_size(&self) -> Option<Size<i32, Logical>> {
+        if self.is_fullscreen() {
+            return None;
+        }
+
         let mut requested = self.requested_size().unwrap_or_default();
         let current = self.size();
         if requested.w == 0 {
@@ -217,7 +222,7 @@ pub trait LayoutElement {
         if requested.h == 0 {
             requested.h = current.h;
         }
-        requested
+        Some(requested)
     }
 
     fn is_child_of(&self, parent: &Self) -> bool;
@@ -2722,7 +2727,8 @@ impl<W: LayoutElement> Layout<W> {
                 if move_.is_floating {
                     let floating_size = move_.tile.floating_window_size();
                     let win = move_.tile.window_mut();
-                    let mut size = floating_size.unwrap_or_else(|| win.expected_size());
+                    let mut size =
+                        floating_size.unwrap_or_else(|| win.expected_size().unwrap_or_default());
                     // Make sure fixed-size through window rules keeps working.
                     let min_size = win.min_size();
                     let max_size = win.max_size();
@@ -3479,7 +3485,9 @@ impl<W: LayoutElement> Layout<W> {
                         // Set the floating size so it takes into account any window resizing that
                         // took place during the move.
                         let mut tile = move_.tile;
-                        tile.set_floating_window_size(tile.window().expected_size());
+                        if let Some(size) = tile.window().expected_size() {
+                            tile.set_floating_window_size(size);
+                        }
 
                         mon.add_floating_tile(ws_idx, tile, Some(pos), true);
                     }
diff --git a/src/tests/floating.rs b/src/tests/floating.rs
index b880745f..ece1a5dc 100644
--- a/src/tests/floating.rs
+++ b/src/tests/floating.rs
@@ -725,3 +725,63 @@ fn interactive_move_restores_floating_size_when_set_to_floating() {
         @""
     );
 }
+
+#[test]
+fn floating_doesnt_store_fullscreen_size() {
+    let mut f = Fixture::new();
+    f.add_output(1, (1920, 1080));
+    f.add_output(2, (1280, 720));
+
+    // Open a window fullscreen.
+    let id = f.add_client();
+    let window = f.client(id).create_window();
+    let surface = window.surface.clone();
+    window.set_fullscreen(None);
+    window.commit();
+    f.roundtrip(id);
+
+    let window = f.client(id).window(&surface);
+    window.attach_new_buffer();
+    window.set_size(1920, 1080);
+    window.ack_last_and_commit();
+    f.double_roundtrip(id);
+
+    let _ = f.client(id).window(&surface).recent_configures();
+
+    // Make it floating.
+    f.niri().layout.toggle_window_floating(None);
+    f.double_roundtrip(id);
+
+    // This should request 0 × 0 to unfullscreen.
+    assert_snapshot!(
+        f.client(id).window(&surface).format_recent_configures(),
+        @"size: 0 × 0, bounds: 1920 × 1080, states: [Activated]"
+    );
+
+    // Without committing, make it tiling again. We never committed while floating, so there's no
+    // floating size to remember.
+    f.niri().layout.toggle_window_floating(None);
+    f.double_roundtrip(id);
+
+    // This should request the tiled size.
+    assert_snapshot!(
+        f.client(id).window(&surface).format_recent_configures(),
+        @"size: 1920 × 1048, bounds: 1888 × 1048, states: [Activated]"
+    );
+
+    // Commit in response.
+    let window = f.client(id).window(&surface);
+    window.set_size(100, 100);
+    window.ack_last_and_commit();
+    f.roundtrip(id);
+
+    // Make the window floating again.
+    f.niri().layout.toggle_window_floating(None);
+    f.double_roundtrip(id);
+
+    // This shouldn't request any size change, particularly not the fullscreen size.
+    assert_snapshot!(
+        f.client(id).window(&surface).format_recent_configures(),
+        @"size: 100 × 100, bounds: 1920 × 1080, states: [Activated]"
+    );
+}
diff --git a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@fsT-wfsAA-spA1.snap b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@fsT-wfsAA-spA1.snap
index e8a53953..dbcb70f1 100644
--- a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@fsT-wfsAA-spA1.snap
+++ b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@fsT-wfsAA-spA1.snap
@@ -12,4 +12,4 @@ size: 1280 × 720, bounds: 1248 × 688, states: [Fullscreen]
 
 post-map configures:
 size: 0 × 0, bounds: 1280 × 720, states: []
-size: 1 × 1, bounds: 1280 × 720, states: [Activated]
+size: 0 × 0, bounds: 1280 × 720, states: [Activated]
diff --git a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@fsT-wfsAA-spA2.snap b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@fsT-wfsAA-spA2.snap
index 5f068979..734218b9 100644
--- a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@fsT-wfsAA-spA2.snap
+++ b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@fsT-wfsAA-spA2.snap
@@ -12,4 +12,4 @@ size: 1280 × 720, bounds: 1248 × 688, states: [Fullscreen]
 
 post-map configures:
 size: 0 × 0, bounds: 1280 × 720, states: []
-size: 1 × 1, bounds: 1280 × 720, states: [Activated]
+size: 0 × 0, bounds: 1280 × 720, states: [Activated]
diff --git a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@fsT-wfsAA-spB1.snap b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@fsT-wfsAA-spB1.snap
index 94af9b36..be7991d7 100644
--- a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@fsT-wfsAA-spB1.snap
+++ b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@fsT-wfsAA-spB1.snap
@@ -12,4 +12,4 @@ size: 1280 × 720, bounds: 1280 × 720, states: [Fullscreen]
 
 post-map configures:
 size: 0 × 0, bounds: 1280 × 720, states: []
-size: 1 × 1, bounds: 1280 × 720, states: [Activated]
+size: 0 × 0, bounds: 1280 × 720, states: [Activated]
diff --git a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@out1-fsT-wfsAA-spA1.snap b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@out1-fsT-wfsAA-spA1.snap
index 245d6712..5e2ed003 100644
--- a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@out1-fsT-wfsAA-spA1.snap
+++ b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@out1-fsT-wfsAA-spA1.snap
@@ -12,4 +12,4 @@ size: 1280 × 720, bounds: 1248 × 688, states: [Fullscreen]
 
 post-map configures:
 size: 0 × 0, bounds: 1280 × 720, states: []
-size: 1 × 1, bounds: 1280 × 720, states: [Activated]
+size: 0 × 0, bounds: 1280 × 720, states: [Activated]
diff --git a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@out1-fsT-wfsAA-spA2.snap b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@out1-fsT-wfsAA-spA2.snap
index d26d382d..08bb2929 100644
--- a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@out1-fsT-wfsAA-spA2.snap
+++ b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@out1-fsT-wfsAA-spA2.snap
@@ -12,4 +12,4 @@ size: 1280 × 720, bounds: 1248 × 688, states: [Fullscreen]
 
 post-map configures:
 size: 0 × 0, bounds: 1280 × 720, states: []
-size: 1 × 1, bounds: 1280 × 720, states: [Activated]
+size: 0 × 0, bounds: 1280 × 720, states: [Activated]
diff --git a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@out1-fsT-wfsAA-spB1.snap b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@out1-fsT-wfsAA-spB1.snap
index 7f1ec39d..6396769d 100644
--- a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@out1-fsT-wfsAA-spB1.snap
+++ b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@out1-fsT-wfsAA-spB1.snap
@@ -12,4 +12,4 @@ size: 1280 × 720, bounds: 1280 × 720, states: [Fullscreen]
 
 post-map configures:
 size: 0 × 0, bounds: 1280 × 720, states: []
-size: 1 × 1, bounds: 1280 × 720, states: [Activated]
+size: 0 × 0, bounds: 1280 × 720, states: [Activated]
diff --git a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@out1-fsT-wfsAA-spB2.snap b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@out1-fsT-wfsAA-spB2.snap
index e2b10554..ca10d9b2 100644
--- a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@out1-fsT-wfsAA-spB2.snap
+++ b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@out1-fsT-wfsAA-spB2.snap
@@ -12,4 +12,4 @@ size: 1280 × 720, bounds: 1280 × 720, states: [Fullscreen]
 
 post-map configures:
 size: 0 × 0, bounds: 1280 × 720, states: []
-size: 1 × 1, bounds: 1280 × 720, states: [Activated]
+size: 0 × 0, bounds: 1280 × 720, states: [Activated]
diff --git a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-fsT-wfsAA-spA1.snap b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-fsT-wfsAA-spA1.snap
index 0e5bcffb..9ebdb8d8 100644
--- a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-fsT-wfsAA-spA1.snap
+++ b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-fsT-wfsAA-spA1.snap
@@ -12,4 +12,4 @@ size: 1280 × 720, bounds: 1248 × 688, states: [Fullscreen]
 
 post-map configures:
 size: 0 × 0, bounds: 1280 × 720, states: []
-size: 1 × 1, bounds: 1280 × 720, states: [Activated]
+size: 0 × 0, bounds: 1280 × 720, states: [Activated]
diff --git a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-fsT-wfsAA-spA2.snap b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-fsT-wfsAA-spA2.snap
index 794b7a11..d4b89fdc 100644
--- a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-fsT-wfsAA-spA2.snap
+++ b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-fsT-wfsAA-spA2.snap
@@ -12,4 +12,4 @@ size: 1280 × 720, bounds: 1248 × 688, states: [Fullscreen]
 
 post-map configures:
 size: 0 × 0, bounds: 1280 × 720, states: []
-size: 1 × 1, bounds: 1280 × 720, states: [Activated]
+size: 0 × 0, bounds: 1280 × 720, states: [Activated]
diff --git a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-fsT-wfsAA-spB1.snap b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-fsT-wfsAA-spB1.snap
index 67cff00f..22e105da 100644
--- a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-fsT-wfsAA-spB1.snap
+++ b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-fsT-wfsAA-spB1.snap
@@ -12,4 +12,4 @@ size: 1280 × 720, bounds: 1280 × 720, states: [Fullscreen]
 
 post-map configures:
 size: 0 × 0, bounds: 1280 × 720, states: []
-size: 1 × 1, bounds: 1280 × 720, states: [Activated]
+size: 0 × 0, bounds: 1280 × 720, states: [Activated]
diff --git a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-fsT-wfsAA-spB2.snap b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-fsT-wfsAA-spB2.snap
index a8621ce9..dba34ea5 100644
--- a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-fsT-wfsAA-spB2.snap
+++ b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-fsT-wfsAA-spB2.snap
@@ -12,4 +12,4 @@ size: 1280 × 720, bounds: 1280 × 720, states: [Fullscreen]
 
 post-map configures:
 size: 0 × 0, bounds: 1280 × 720, states: []
-size: 1 × 1, bounds: 1280 × 720, states: [Activated]
+size: 0 × 0, bounds: 1280 × 720, states: [Activated]
diff --git a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out1-fsT-wfsAA-spA1.snap b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out1-fsT-wfsAA-spA1.snap
index 6d9f0828..0b35423b 100644
--- a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out1-fsT-wfsAA-spA1.snap
+++ b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out1-fsT-wfsAA-spA1.snap
@@ -12,4 +12,4 @@ size: 1280 × 720, bounds: 1248 × 688, states: [Fullscreen]
 
 post-map configures:
 size: 0 × 0, bounds: 1280 × 720, states: []
-size: 1 × 1, bounds: 1280 × 720, states: [Activated]
+size: 0 × 0, bounds: 1280 × 720, states: [Activated]
diff --git a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out1-fsT-wfsAA-spA2.snap b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out1-fsT-wfsAA-spA2.snap
index 950503cc..ca0aea42 100644
--- a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out1-fsT-wfsAA-spA2.snap
+++ b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out1-fsT-wfsAA-spA2.snap
@@ -12,4 +12,4 @@ size: 1280 × 720, bounds: 1248 × 688, states: [Fullscreen]
 
 post-map configures:
 size: 0 × 0, bounds: 1280 × 720, states: []
-size: 1 × 1, bounds: 1280 × 720, states: [Activated]
+size: 0 × 0, bounds: 1280 × 720, states: [Activated]
diff --git a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out1-fsT-wfsAA-spB1.snap b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out1-fsT-wfsAA-spB1.snap
index 79628535..765241e4 100644
--- a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out1-fsT-wfsAA-spB1.snap
+++ b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out1-fsT-wfsAA-spB1.snap
@@ -12,4 +12,4 @@ size: 1280 × 720, bounds: 1280 × 720, states: [Fullscreen]
 
 post-map configures:
 size: 0 × 0, bounds: 1280 × 720, states: []
-size: 1 × 1, bounds: 1280 × 720, states: [Activated]
+size: 0 × 0, bounds: 1280 × 720, states: [Activated]
diff --git a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out1-fsT-wfsAA-spB2.snap b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out1-fsT-wfsAA-spB2.snap
index d97e1dcc..f8c022be 100644
--- a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out1-fsT-wfsAA-spB2.snap
+++ b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out1-fsT-wfsAA-spB2.snap
@@ -12,4 +12,4 @@ size: 1280 × 720, bounds: 1280 × 720, states: [Fullscreen]
 
 post-map configures:
 size: 0 × 0, bounds: 1280 × 720, states: []
-size: 1 × 1, bounds: 1280 × 720, states: [Activated]
+size: 0 × 0, bounds: 1280 × 720, states: [Activated]
diff --git a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out2-fsT-wfsAA-spA1.snap b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out2-fsT-wfsAA-spA1.snap
index 2708f587..932a6ad7 100644
--- a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out2-fsT-wfsAA-spA1.snap
+++ b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out2-fsT-wfsAA-spA1.snap
@@ -12,4 +12,4 @@ size: 1280 × 720, bounds: 1248 × 688, states: [Fullscreen]
 
 post-map configures:
 size: 0 × 0, bounds: 1280 × 720, states: []
-size: 1 × 1, bounds: 1280 × 720, states: [Activated]
+size: 0 × 0, bounds: 1280 × 720, states: [Activated]
diff --git a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out2-fsT-wfsAA-spA2.snap b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out2-fsT-wfsAA-spA2.snap
index aae7b880..055c467c 100644
--- a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out2-fsT-wfsAA-spA2.snap
+++ b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out2-fsT-wfsAA-spA2.snap
@@ -12,4 +12,4 @@ size: 1280 × 720, bounds: 1248 × 688, states: [Fullscreen]
 
 post-map configures:
 size: 0 × 0, bounds: 1280 × 720, states: []
-size: 1 × 1, bounds: 1280 × 720, states: [Activated]
+size: 0 × 0, bounds: 1280 × 720, states: [Activated]
diff --git a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out2-fsT-wfsAA-spB1.snap b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out2-fsT-wfsAA-spB1.snap
index 396d54d1..21a35d38 100644
--- a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out2-fsT-wfsAA-spB1.snap
+++ b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out2-fsT-wfsAA-spB1.snap
@@ -12,4 +12,4 @@ size: 1280 × 720, bounds: 1280 × 720, states: [Fullscreen]
 
 post-map configures:
 size: 0 × 0, bounds: 1280 × 720, states: []
-size: 1 × 1, bounds: 1280 × 720, states: [Activated]
+size: 0 × 0, bounds: 1280 × 720, states: [Activated]
diff --git a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out2-fsT-wfsAA-spB2.snap b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out2-fsT-wfsAA-spB2.snap
index bdbdf330..e5720dd4 100644
--- a/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out2-fsT-wfsAA-spB2.snap
+++ b/src/tests/snapshots/niri__tests__window_opening__check_target_output_and_workspace@ws1-out2-fsT-wfsAA-spB2.snap
@@ -12,4 +12,4 @@ size: 1280 × 720, bounds: 1280 × 720, states: [Fullscreen]
 
 post-map configures:
 size: 0 × 0, bounds: 1280 × 720, states: []
-size: 1 × 1, bounds: 1280 × 720, states: [Activated]
+size: 0 × 0, bounds: 1280 × 720, states: [Activated]
diff --git a/src/window/mapped.rs b/src/window/mapped.rs
index 5f5f6c3e..022a57a0 100644
--- a/src/window/mapped.rs
+++ b/src/window/mapped.rs
@@ -829,8 +829,9 @@ impl LayoutElement for Mapped {
         self.toplevel().with_pending_state(|state| state.size)
     }
 
-    fn expected_size(&self) -> Size<i32, Logical> {
-        let current_size = self.window.geometry().size;
+    fn expected_size(&self) -> Option<Size<i32, Logical>> {
+        // We can only use current size if it's not fullscreen.
+        let current_size = (!self.is_fullscreen()).then(|| self.window.geometry().size);
 
         // Check if we should be using the current window size.
         //
@@ -849,12 +850,17 @@ impl LayoutElement for Mapped {
             return current_size;
         }
 
-        let pending_size = with_toplevel_role(self.toplevel(), |role| {
+        let pending = with_toplevel_role(self.toplevel(), |role| {
             // If we have a server-pending size change that we haven't sent yet, use that size.
             if let Some(server_pending) = &role.server_pending {
                 let current_server = role.current_server_state();
                 if server_pending.size != current_server.size {
-                    return Some(server_pending.size.unwrap_or_default());
+                    return Some((
+                        server_pending.size.unwrap_or_default(),
+                        server_pending
+                            .states
+                            .contains(xdg_toplevel::State::Fullscreen),
+                    ));
                 }
             }
 
@@ -871,23 +877,36 @@ impl LayoutElement for Mapped {
 
             if let Some(current_serial) = role.current_serial {
                 if !current_serial.is_no_older_than(&last_serial) {
-                    return Some(last_sent.size.unwrap_or_default());
+                    return Some((
+                        last_sent.size.unwrap_or_default(),
+                        last_sent.states.contains(xdg_toplevel::State::Fullscreen),
+                    ));
                 }
             }
 
             None
         });
 
-        // If we have no pending size change (size change that the window hasn't committed to), or
-        // if some component of the pending size change is zero, use the current window size.
-        let mut size = pending_size.unwrap_or_default();
-        if size.w == 0 {
-            size.w = current_size.w;
-        }
-        if size.h == 0 {
-            size.h = current_size.h;
+        if let Some((mut size, fullscreen)) = pending {
+            // If the pending change is fullscreen, we can't use that size.
+            if fullscreen {
+                return None;
+            }
+
+            // If some component of the pending size is zero, substitute it with the current window
+            // size. But only if the current size is not fullscreen.
+            if size.w == 0 {
+                size.w = current_size?.w;
+            }
+            if size.h == 0 {
+                size.h = current_size?.h;
+            }
+
+            Some(size)
+        } else {
+            // No pending size, return the current size if it's non-fullscreen.
+            current_size
         }
-        size
     }
 
     fn is_child_of(&self, parent: &Self) -> bool {