WindowServer: Recompute occlusions when changing window's alpha channel

Fixes #4845

2 files changed, 10 insertions, 2 deletions

diff --git a/Userland/Services/WindowServer/Window.cpp b/Userland/Services/WindowServer/Window.cpp
index 0a28629e16..544d19ee49 100644
--- a/Userland/Services/WindowServer/Window.cpp
+++ b/Userland/Services/WindowServer/Window.cpp
@@ -323,10 +323,18 @@ void Window::set_opacity(float opacity)
     m_opacity = opacity;
     if (was_opaque != is_opaque())
         Compositor::the().invalidate_occlusions();
-    Compositor::the().invalidate_screen(frame().render_rect());
+    invalidate(false);
     WindowManager::the().notify_opacity_changed(*this);
 }
 
+void Window::set_has_alpha_channel(bool value)
+{
+    if (m_has_alpha_channel == value)
+        return;
+    m_has_alpha_channel = value;
+    Compositor::the().invalidate_occlusions();
+}
+
 void Window::set_occluded(bool occluded)
 {
     if (m_occluded == occluded)
diff --git a/Userland/Services/WindowServer/Window.h b/Userland/Services/WindowServer/Window.h
index 02de18c0bd..53c39a1524 100644
--- a/Userland/Services/WindowServer/Window.h
+++ b/Userland/Services/WindowServer/Window.h
@@ -219,7 +219,7 @@ public:
     bool global_cursor_tracking() const { return m_global_cursor_tracking_enabled || m_automatic_cursor_tracking_enabled; }
 
     bool has_alpha_channel() const { return m_has_alpha_channel; }
-    void set_has_alpha_channel(bool value) { m_has_alpha_channel = value; }
+    void set_has_alpha_channel(bool value);
 
     Gfx::IntSize size_increment() const { return m_size_increment; }
     void set_size_increment(const Gfx::IntSize& increment) { m_size_increment = increment; }