Use Qt's event loop instead of polling for events

This fixes slow input event handling execution on Linux. Additionally,
it seems to fix some crashes with the menu bar.

src/editor/C4ConsoleQtState.cpp

@@ -537,31 +537,13 @@ bool C4ConsoleGUIState::CreateConsoleWindow(C4AbstractApp *app)
 	HWND hWindow = reinterpret_cast<HWND>(window->winId());
 	RestoreWindowPosition(hWindow, "Main", Config.GetSubkeyPath("Console"));
 #endif
+
 	return true;
 }
 
 void C4ConsoleGUIState::Execute(bool redraw_only)
 {
-	// Avoid recursion in message processing; it's causing random crashes
-	ExecRecursionCheck recursion_check;
-	if (recursion_check.IsRecursion()) return;
-	// Qt window message handling and object cleanup
-	if (application)
-	{
-		if (redraw_only)
-		{
-			// process only non-critical events
-			// redrawing only allowed during GameTick; prevent callbacks within a Qt event triggered by windows messaging
-			if (::Application.IsInGameTick())
-				application->processEvents(QEventLoop::ExcludeUserInputEvents);
-		}
-		else
-		{
-			// process everything
-			application->processEvents();
-			application->sendPostedEvents(0, QEvent::DeferredDelete);
-		}
-	}
+	// Nothing to do - Qt's event loop is handling everything.
 }
 
 // Set action pressed/checked and enabled states

src/platform/C4App.cpp

@@ -18,8 +18,31 @@
 #include "platform/C4App.h"
 #include "platform/C4Window.h"
 
+#ifdef WITH_QT_EDITOR
+#include "game/C4Application.h"
+#include "editor/C4ConsoleQt.h"
+#endif
+
 void C4AbstractApp::Run()
 {
+#ifdef WITH_QT_EDITOR
+	if (Application.isEditor)
+	{
+		// Qt has its own event loop. Use a timer to call our own event handling whenever Qt is done
+		// with its events (zero timeout). The alternative (calling Qt's event handling from
+		// C4Console::Execute) is too slow, at least on Linux.
+		QTimer timer;
+		QObject::connect(&timer, &QTimer::timeout, [this]() {
+			ScheduleProcs(0);
+			if (fQuitMsgReceived)
+				QApplication::quit();
+		});
+		timer.start();
+		QApplication::exec();
+		return;
+	}
+#endif
+
 	// Main message loop
 	while (!fQuitMsgReceived)
 		ScheduleProcs();