Avoid enqueuing events directly to laf-os

src/app/ui/timeline/timeline.cpp

@@ -55,8 +55,6 @@
 #include "fmt/format.h"
 #include "gfx/point.h"
 #include "gfx/rect.h"
-#include "os/event.h"
-#include "os/event_queue.h"
 #include "os/surface.h"
 #include "os/system.h"
 #include "text/font.h"
@@ -4496,8 +4494,7 @@ void Timeline::onDragLeave(ui::DragEvent& e)
   m_dropRange.clearRange();
   invalidate();
   flushRedraw();
-  os::Event ev;
-  os::System::instance()->eventQueue()->queueEvent(ev);
+  flushMessages();
 }
 
 void Timeline::onDrag(ui::DragEvent& e)
@@ -4526,8 +4523,7 @@ void Timeline::onDrag(ui::DragEvent& e)
 
   updateDropRange(e.position());
   flushRedraw();
-  os::Event ev;
-  os::System::instance()->eventQueue()->queueEvent(ev);
+  flushMessages();
 }
 
 void Timeline::onDrop(ui::DragEvent& e)
@@ -4603,8 +4599,7 @@ void Timeline::onDrop(ui::DragEvent& e)
   m_dropRange.clearRange();
   invalidate();
   flushRedraw();
-  os::Event ev;
-  os::System::instance()->eventQueue()->queueEvent(ev);
+  flushMessages();
 }
 
 int Timeline::tagFramesDuration(const Tag* tag) const

src/ui/manager.cpp

@@ -881,6 +881,13 @@ void Manager::dispatchMessages()
   }
 }
 
+void Manager::flushMessages() const
+{
+  // Send a dummy event just to break the waiting loop.
+  os::Event evt;
+  m_eventQueue->queueEvent(evt);
+}
+
 void Manager::addToGarbage(Widget* widget)
 {
   ASSERT(widget);

src/ui/manager.h

@@ -63,6 +63,10 @@ public:
   bool generateMessages();
   void dispatchMessages();
 
+  // Wakes up the system's events queue to process the currently enqueued UI
+  // messages.
+  void flushMessages() const;
+
   // Makes the generateMessages() function to return immediately if
   // there is no user events in the OS queue. Useful only for tests
   // or benchmarks where we don't wait the user (or we don't even

src/ui/widget.cpp

@@ -1176,6 +1176,16 @@ void Widget::flushRedraw()
   }
 }
 
+void Widget::flushMessages() const
+{
+  Manager* manager = this->manager();
+  ASSERT(manager);
+  if (!manager)
+    return;
+
+  manager->flushMessages();
+}
+
 void Widget::paint(Graphics* graphics, const gfx::Region& drawRegion, const bool isBg)
 {
   if (drawRegion.isEmpty())

src/ui/widget.h

@@ -313,6 +313,10 @@ public:
   // Generates paint messages for the current update region.
   void flushRedraw();
 
+  // Wakes up the system's events queue to process the currently enqueued UI
+  // messages.
+  void flushMessages() const;
+
   GraphicsPtr getGraphics(const gfx::Rect& clip);
 
   // ===============================================================