fix: handle fullscreen windows on special workspaces (#12851)

* fix: handle fullscreen windows on special workspaces

inFullscreenMode() only checked m_activeWorkspace, missing fullscreen
windows on special workspaces. This caused crashes and incorrect
behavior when fullscreen windows were on special workspaces.

Changes:
- inFullscreenMode() now checks special workspace first since it
  renders on top of regular workspaces
- Added getFullscreenWindow() helper to safely get fullscreen window
  from either active or special workspace
- Updated callers (shouldSkipScheduleFrameOnMouseEvent, Renderer,
  getFSImageDescription) to use the new helper
- Reset m_aboveFullscreen for layer surfaces when opening, closing,
  or stealing special workspaces between monitors

* test: add special workspace fullscreen detection tests

Add tests for the new special workspace fullscreen handling introduced
in the previous commit. The tests cover:

1. Fullscreen detection on special workspace - verifies that a window
   made fullscreen on a special workspace is correctly detected

2. Special workspace fullscreen precedence - verifies that when both
   regular and special workspaces have fullscreen windows, the special
   workspace window can be focused when the special workspace is opened

3. Toggle special workspace behavior - verifies that toggling the
   special workspace off properly hides it and returns focus to the
   regular workspace's fullscreen window

These tests exercise the key code paths modified in the fix:
- inFullscreenMode() checking special workspace first
- getFullscreenWindow() helper returning correct window
- Layer surface m_aboveFullscreen reset on special workspace toggle

hyprtester/src/tests/main/workspaces.cpp

@@ -20,6 +20,91 @@ using namespace Hyprutils::Utils;
 #define UP CUniquePointer
 #define SP CSharedPointer
 
+static bool testSpecialWorkspaceFullscreen() {
+    NLog::log("{}Testing special workspace fullscreen detection", Colors::YELLOW);
+
+    CScopeGuard guard = {[&]() {
+        NLog::log("{}Cleaning up special workspace fullscreen test", Colors::YELLOW);
+        // Close special workspace if open
+        auto monitors = getFromSocket("/monitors");
+        if (monitors.contains("(special:test_fs_special)") && !monitors.contains("special workspace: 0 ()"))
+            getFromSocket("/dispatch togglespecialworkspace test_fs_special");
+        Tests::killAllWindows();
+        OK(getFromSocket("/reload"));
+    }};
+
+    getFromSocket("/dispatch workspace 1");
+    EXPECT(Tests::windowCount(), 0);
+
+    NLog::log("{}Test 1: Fullscreen detection on special workspace", Colors::YELLOW);
+
+    OK(getFromSocket("/dispatch workspace special:test_fs_special"));
+
+    if (!Tests::spawnKitty("kitty_special"))
+        return false;
+
+    {
+        auto str = getFromSocket("/activewindow");
+        EXPECT_CONTAINS(str, "class: kitty_special");
+        EXPECT_CONTAINS(str, "(special:test_fs_special)");
+    }
+
+    OK(getFromSocket("/dispatch fullscreen 0"));
+
+    {
+        auto str = getFromSocket("/activewindow");
+        EXPECT_CONTAINS(str, "fullscreen: 2");
+    }
+
+    {
+        auto str = getFromSocket("/monitors");
+        EXPECT_CONTAINS(str, "(special:test_fs_special)");
+    }
+
+    NLog::log("{}Test 2: Special workspace fullscreen precedence", Colors::YELLOW);
+
+    // Close special workspace before spawning on regular workspace
+    OK(getFromSocket("/dispatch togglespecialworkspace test_fs_special"));
+    getFromSocket("/dispatch workspace 1");
+
+    if (!Tests::spawnKitty("kitty_regular"))
+        return false;
+
+    OK(getFromSocket("/dispatch fullscreen 0"));
+
+    {
+        auto str = getFromSocket("/activewindow");
+        EXPECT_CONTAINS(str, "class: kitty_regular");
+        EXPECT_CONTAINS(str, "fullscreen: 2");
+    }
+
+    OK(getFromSocket("/dispatch togglespecialworkspace test_fs_special"));
+    OK(getFromSocket("/dispatch focuswindow class:kitty_special"));
+
+    {
+        auto str = getFromSocket("/activewindow");
+        EXPECT_CONTAINS(str, "class: kitty_special");
+    }
+
+    NLog::log("{}Test 3: Toggle special workspace hides it", Colors::YELLOW);
+
+    OK(getFromSocket("/dispatch togglespecialworkspace test_fs_special"));
+    OK(getFromSocket("/dispatch focuswindow class:kitty_regular"));
+
+    {
+        auto str = getFromSocket("/activewindow");
+        EXPECT_CONTAINS(str, "class: kitty_regular");
+        EXPECT_CONTAINS(str, "fullscreen: 2");
+    }
+
+    {
+        auto str = getFromSocket("/monitors");
+        EXPECT_CONTAINS(str, "special workspace: 0 ()");
+    }
+
+    return true;
+}
+
 static bool testAsymmetricGaps() {
     NLog::log("{}Testing asymmetric gap splits", Colors::YELLOW);
     {
@@ -449,6 +534,8 @@ static bool test() {
     NLog::log("{}Killing all windows", Colors::YELLOW);
     Tests::killAllWindows();
 
+    testSpecialWorkspaceFullscreen();
+
     testAsymmetricGaps();
 
     NLog::log("{}Expecting 0 windows", Colors::YELLOW);