WindowServer: Flash modal window when clicking on window blocked by it

This makes window modality a bit more discoverable by indicating to the
user that the modal window must be closed before mouse interaction is
possible in the clicked window.

Services/WindowServer/WindowFrame.cpp

@@ -160,6 +160,10 @@ Gfx::IntRect WindowFrame::title_bar_text_rect() const
 Gfx::WindowTheme::WindowState WindowFrame::window_state_for_theme() const
 {
  auto& wm = WindowManager::the();
+
+ if (m_flash_timer && m_flash_timer->is_active())
+ return m_flash_counter & 1 ? Gfx::WindowTheme::WindowState::Active : Gfx::WindowTheme::WindowState::Inactive;
+
  if (&m_window == wm.m_highlight_window)
  return Gfx::WindowTheme::WindowState::Highlighted;
  if (&m_window == wm.m_move_window)
@@ -360,4 +364,19 @@ void WindowFrame::on_mouse_event(const MouseEvent& event)
  if (m_window.is_resizable() && event.type() == Event::MouseDown && event.button() == MouseButton::Left)
  wm.start_window_resize(m_window, event.translated(rect().location()));
 }
+
+void WindowFrame::start_flash_animation()
+{
+ if (!m_flash_timer) {
+ m_flash_timer = Core::Timer::construct(100, [this] {
+ ASSERT(m_flash_counter);
+ invalidate_title_bar();
+ if (!--m_flash_counter)
+ m_flash_timer->stop();
+ });
+ }
+ m_flash_counter = 8;
+ m_flash_timer->start();
+}
+
 }

Services/WindowServer/WindowFrame.h

@@ -28,6 +28,8 @@
 
 #include <AK/Forward.h>
 #include <AK/NonnullOwnPtrVector.h>
+#include <AK/RefPtr.h>
+#include <LibCore/Forward.h>
 #include <LibGfx/Forward.h>
 #include <LibGfx/WindowTheme.h>
 
@@ -58,6 +60,8 @@ class WindowFrame {
  void layout_buttons();
  void set_button_icons();
 
+ void start_flash_animation();
+
 private:
  void paint_notification_frame(Gfx::Painter&);
  void paint_normal_frame(Gfx::Painter&);
@@ -69,6 +73,9 @@ class WindowFrame {
  Button* m_close_button { nullptr };
  Button* m_maximize_button { nullptr };
  Button* m_minimize_button { nullptr };
+
+ RefPtr<Core::Timer> m_flash_timer;
+ size_t m_flash_counter { 0 };
 };
 
 }

Services/WindowServer/WindowManager.cpp

@@ -996,6 +996,11 @@ void WindowManager::process_mouse_event(MouseEvent& event, Window*& hovered_wind
  // Well okay, let's see if we're hitting the frame or the window inside the frame.
  if (window.rect().contains(event.position())) {
  if (event.type() == Event::MouseDown) {
+ // We're clicking on something that's blocked by a modal window.
+ // Flash the modal window to let the user know about it.
+ if (auto* blocking_modal_window = window.is_blocked_by_modal_window())
+ blocking_modal_window->frame().start_flash_animation();
+
  if (window.type() == WindowType::Normal)
  move_to_front_and_make_active(window);
  else if (window.type() == WindowType::Desktop)