Add transparent overlay window (#4746)

src/singletons/WindowManager.cpp

@@ -16,6 +16,7 @@
 #include "widgets/FramelessEmbedWindow.hpp"
 #include "widgets/helper/NotebookTab.hpp"
 #include "widgets/Notebook.hpp"
+#include "widgets/OverlayWindow.hpp"
 #include "widgets/splits/Split.hpp"
 #include "widgets/splits/SplitContainer.hpp"
 #include "widgets/Window.hpp"
@@ -544,6 +545,37 @@ void WindowManager::queueSave()
     this->saveTimer->start(10s);
 }
 
+void WindowManager::toggleAllOverlayInertia()
+{
+    // check if any window is not inert
+    bool anyNonInert = false;
+    for (auto *window : this->windows_)
+    {
+        if (anyNonInert)
+        {
+            break;
+        }
+        window->getNotebook().forEachSplit([&](auto *split) {
+            auto *overlay = split->overlayWindow();
+            if (overlay)
+            {
+                anyNonInert = anyNonInert || !overlay->isInert();
+            }
+        });
+    }
+
+    for (auto *window : this->windows_)
+    {
+        window->getNotebook().forEachSplit([&](auto *split) {
+            auto *overlay = split->overlayWindow();
+            if (overlay)
+            {
+                overlay->setInert(anyNonInert);
+            }
+        });
+    }
+}
+
 void WindowManager::encodeTab(SplitContainer *tab, bool isSelected,
                               QJsonObject &obj)
 {