Qt: Don't attempt to draw a frame if holding an interrupter

src/platform/qt/CoreController.cpp

@@ -1358,3 +1358,7 @@ void CoreController::Interrupter::resume(CoreController* controller) {
 
 	mCoreThreadContinue(controller->thread());
 }
+
+bool CoreController::Interrupter::held() const {
+	return m_parent && m_parent->thread()->impl;
+}

src/platform/qt/CoreController.h

@@ -68,6 +68,8 @@ public:
 		void interrupt(std::shared_ptr<CoreController>);
 		void resume();
 
+		bool held() const;
+
 	private:
 		void interrupt();
 		void resume(CoreController*);

src/platform/qt/DisplayGL.cpp

@@ -626,6 +626,15 @@ void PainterGL::draw() {
 	if (!m_started || m_queue.isEmpty()) {
 		return;
 	}
+
+	if (m_interrupter.held()) {
+		// A resize event is pending; that needs to happen first
+		if (!m_drawTimer.isActive()) {
+			m_drawTimer.start(0);
+		}
+		return;
+	}
+
 	mCoreSync* sync = &m_context->thread()->impl->sync;
 	if (!mCoreSyncWaitFrameStart(sync)) {
 		mCoreSyncWaitFrameEnd(sync);