diff --git a/panels/effectcontrols.cpp b/panels/effectcontrols.cpp
index 392423e89..d9ca18dad 100644
--- a/panels/effectcontrols.cpp
+++ b/panels/effectcontrols.cpp
@@ -34,7 +34,7 @@ EffectControls::EffectControls(QWidget *parent) :
 	QDockWidget(parent),
 	multiple(false),
 	zoom(1),
-    panel_name(tr("Effects: ")),
+	panel_name(tr("Effects: ")),
 	mode(TA_NO_TRANSITION)
 {
 	setSizePolicy(QSizePolicy::Fixed, QSizePolicy::Fixed);
@@ -94,7 +94,7 @@ void EffectControls::menu_select(QAction* q) {
 		update_ui(true);
 	} else {
 		reload_clips();
-		panel_sequence_viewer->viewer_widget->update();
+		panel_sequence_viewer->viewer_widget->frame_update();
 	}
 }
 
@@ -303,7 +303,7 @@ void EffectControls::setup_ui() {
 
 	QPushButton* btnAddVideoEffect = new QPushButton(veHeader);
 	btnAddVideoEffect->setIcon(QIcon(":/icons/add-effect.png"));
-    btnAddVideoEffect->setToolTip(tr("Add Video Effect"));
+	btnAddVideoEffect->setToolTip(tr("Add Video Effect"));
 	veHeaderLayout->addWidget(btnAddVideoEffect);
 	connect(btnAddVideoEffect, SIGNAL(clicked(bool)), this, SLOT(video_effect_click()));
 
@@ -314,14 +314,14 @@ void EffectControls::setup_ui() {
 	font.setPointSize(9);
 	lblVideoEffects->setFont(font);
 	lblVideoEffects->setAlignment(Qt::AlignCenter);
-    lblVideoEffects->setText(tr("VIDEO EFFECTS"));
+	lblVideoEffects->setText(tr("VIDEO EFFECTS"));
 	veHeaderLayout->addWidget(lblVideoEffects);
 
 	veHeaderLayout->addStretch();
 
 	QPushButton* btnAddVideoTransition = new QPushButton(veHeader);
 	btnAddVideoTransition->setIcon(QIcon(":/icons/add-transition.png"));
-    btnAddVideoTransition->setToolTip(tr("Add Video Transition"));
+	btnAddVideoTransition->setToolTip(tr("Add Video Transition"));
 	connect(btnAddVideoTransition, SIGNAL(clicked(bool)), this, SLOT(video_transition_click()));
 
 	veHeaderLayout->addWidget(btnAddVideoTransition);
@@ -351,7 +351,7 @@ void EffectControls::setup_ui() {
 
 	QPushButton* btnAddAudioEffect = new QPushButton(aeHeader);
 	btnAddAudioEffect->setIcon(QIcon(":/icons/add-effect.png"));
-    btnAddAudioEffect->setToolTip(tr("Add Audio Effect"));
+	btnAddAudioEffect->setToolTip(tr("Add Audio Effect"));
 	connect(btnAddAudioEffect, SIGNAL(clicked(bool)), this, SLOT(audio_effect_click()));
 	aeHeaderLayout->addWidget(btnAddAudioEffect);
 
@@ -360,14 +360,14 @@ void EffectControls::setup_ui() {
 	QLabel* lblAudioEffects = new QLabel(aeHeader);
 	lblAudioEffects->setFont(font);
 	lblAudioEffects->setAlignment(Qt::AlignCenter);
-    lblAudioEffects->setText(tr("AUDIO EFFECTS"));
+	lblAudioEffects->setText(tr("AUDIO EFFECTS"));
 	aeHeaderLayout->addWidget(lblAudioEffects);
 
 	aeHeaderLayout->addStretch();
 
 	QPushButton* btnAddAudioTransition = new QPushButton(aeHeader);
 	btnAddAudioTransition->setIcon(QIcon(":/icons/add-transition.png"));
-    btnAddAudioTransition->setToolTip(tr("Add Audio Transition"));
+	btnAddAudioTransition->setToolTip(tr("Add Audio Transition"));
 	connect(btnAddAudioTransition, SIGNAL(clicked(bool)), this, SLOT(audio_transition_click()));
 	aeHeaderLayout->addWidget(btnAddAudioTransition);
 
@@ -384,7 +384,7 @@ void EffectControls::setup_ui() {
 
 	lblMultipleClipsSelected = new QLabel(effects_area);
 	lblMultipleClipsSelected->setAlignment(Qt::AlignCenter);
-    lblMultipleClipsSelected->setText(tr("(Multiple clips selected)"));
+	lblMultipleClipsSelected->setText(tr("(Multiple clips selected)"));
 	effects_area_layout->addWidget(lblMultipleClipsSelected);
 
 	effects_area_layout->addStretch();
diff --git a/playback/playback.cpp b/playback/playback.cpp
index edd55a98b..4e16d8d54 100644
--- a/playback/playback.cpp
+++ b/playback/playback.cpp
@@ -33,7 +33,6 @@ extern "C" {
 //#define GCF_DEBUG
 #endif
 
-bool texture_failed = false;
 bool rendering = false;
 
 long refactor_frame_number(long framenumber, double source_frame_rate, double target_frame_rate) {
@@ -122,7 +121,7 @@ double get_timecode(Clip* c, long playhead) {
 	return ((double)(playhead-c->get_timeline_in_with_transition()+c->get_clip_in_with_transition())/(double)c->sequence->frame_rate);
 }
 
-void get_clip_frame(Clip* c, long playhead) {
+void get_clip_frame(Clip* c, long playhead, bool& texture_failed) {
 	if (c->finished_opening) {
 		const FootageStream* ms = c->media->to_footage()->get_stream_from_file_index(c->track < 0, c->media_stream);
 
@@ -249,7 +248,7 @@ void get_clip_frame(Clip* c, long playhead) {
 		if (target_frame == nullptr || reset) {
 			// reset cache
 			texture_failed = true;
-//			qInfo() << "Frame queue couldn't keep up - either the user seeked or the system is overloaded (queue size:" << c->queue.size() << ")";
+			qInfo() << "Frame queue couldn't keep up - either the user seeked or the system is overloaded (queue size:" << c->queue.size() << ")";
 		}
 
 		if (target_frame != nullptr) {
diff --git a/playback/playback.h b/playback/playback.h
index 914ea42fa..df81c1183 100644
--- a/playback/playback.h
+++ b/playback/playback.h
@@ -9,7 +9,6 @@ struct ClipCache;
 struct Sequence;
 struct AVFrame;
 
-extern bool texture_failed;
 extern bool rendering;
 
 long refactor_frame_number(long framenumber, double source_frame_rate, double target_frame_rate);
@@ -21,7 +20,7 @@ void cache_audio_worker(Clip* c, bool write_A);
 void cache_video_worker(Clip* c, long playhead);
 void handle_media(Sequence* sequence, long playhead, bool multithreaded);
 void reset_cache(Clip* c, long target_frame);
-void get_clip_frame(Clip* c, long playhead);
+void get_clip_frame(Clip* c, long playhead, bool &texture_failed);
 double get_timecode(Clip* c, long playhead);
 
 long playhead_to_clip_frame(Clip* c, long playhead);
diff --git a/project/effect.cpp b/project/effect.cpp
index 4d8109f43..e777335c1 100644
--- a/project/effect.cpp
+++ b/project/effect.cpp
@@ -537,7 +537,7 @@ int Effect::gizmo_count(){
 void Effect::refresh() {}
 
 void Effect::field_changed() {
-	panel_sequence_viewer->viewer_widget->update();
+	panel_sequence_viewer->viewer_widget->frame_update();
 	panel_graph_editor->update_panel();
 }
 
diff --git a/ui/renderfunctions.cpp b/ui/renderfunctions.cpp
index 2971f3703..636cb1a0f 100644
--- a/ui/renderfunctions.cpp
+++ b/ui/renderfunctions.cpp
@@ -83,6 +83,7 @@ void process_effect(QOpenGLContext* ctx,
 					GLTextureCoords& coords,
 					GLuint& composite_texture,
 					bool& fbo_switcher,
+					bool& texture_failed,
 					int data) {
 	if (e->is_enabled()) {
 		if (e->enable_coords) {
@@ -115,7 +116,8 @@ GLuint compose_sequence(Viewer* viewer,
 						QVector<Clip*>& nests,
 						bool video,
 						bool render_audio,
-						Effect** gizmos) {
+						Effect** gizmos,
+						bool& texture_failed) {
 	GLint current_fbo = 0;
 	if (video) {
 		glGetIntegerv(GL_DRAW_FRAMEBUFFER_BINDING, &current_fbo);
@@ -235,7 +237,7 @@ GLuint compose_sequence(Viewer* viewer,
 							c->texture->setMinMagFilters(QOpenGLTexture::Linear, QOpenGLTexture::Linear);
 							c->texture->allocateStorage(get_gl_pix_fmt_from_av(c->pix_fmt), QOpenGLTexture::UInt8);
 						}
-						get_clip_frame(c, playhead);
+						get_clip_frame(c, playhead, texture_failed);
 						textureID = c->texture->textureId();
 						break;
 					case MEDIA_TYPE_SEQUENCE:
@@ -281,7 +283,7 @@ GLuint compose_sequence(Viewer* viewer,
 						// for nested sequences
 						if (c->media->get_type()== MEDIA_TYPE_SEQUENCE) {
 							nests.append(c);
-							textureID = compose_sequence(viewer, ctx, seq, nests, video, render_audio, gizmos);
+							textureID = compose_sequence(viewer, ctx, seq, nests, video, render_audio, gizmos, texture_failed);
 							nests.removeLast();
 							fbo_switcher = true;
 						}
@@ -319,7 +321,7 @@ GLuint compose_sequence(Viewer* viewer,
 
 					for (int j=0;j<c->effects.size();j++) {
 						Effect* e = c->effects.at(j);
-						process_effect(ctx, c, e, timecode, coords, composite_texture, fbo_switcher, TA_NO_TRANSITION);
+						process_effect(ctx, c, e, timecode, coords, composite_texture, fbo_switcher, texture_failed, TA_NO_TRANSITION);
 
 						if (e->are_gizmos_enabled()) {
 							if (first_gizmo_effect == nullptr) first_gizmo_effect = e;
@@ -338,14 +340,14 @@ GLuint compose_sequence(Viewer* viewer,
 					if (c->get_opening_transition() != nullptr) {
 						int transition_progress = playhead - c->get_timeline_in_with_transition();
 						if (transition_progress < c->get_opening_transition()->get_length()) {
-							process_effect(ctx, c, c->get_opening_transition(), (double)transition_progress/(double)c->get_opening_transition()->get_length(), coords, composite_texture, fbo_switcher, TA_OPENING_TRANSITION);
+							process_effect(ctx, c, c->get_opening_transition(), (double)transition_progress/(double)c->get_opening_transition()->get_length(), coords, composite_texture, fbo_switcher, texture_failed, TA_OPENING_TRANSITION);
 						}
 					}
 
 					if (c->get_closing_transition() != nullptr) {
 						int transition_progress = playhead - (c->get_timeline_out_with_transition() - c->get_closing_transition()->get_length());
 						if (transition_progress >= 0 && transition_progress < c->get_closing_transition()->get_length()) {
-							process_effect(ctx, c, c->get_closing_transition(), (double)transition_progress/(double)c->get_closing_transition()->get_length(), coords, composite_texture, fbo_switcher, TA_CLOSING_TRANSITION);
+							process_effect(ctx, c, c->get_closing_transition(), (double)transition_progress/(double)c->get_closing_transition()->get_length(), coords, composite_texture, fbo_switcher, texture_failed, TA_CLOSING_TRANSITION);
 						}
 					}
 					// EFFECT CODE END
@@ -452,7 +454,7 @@ GLuint compose_sequence(Viewer* viewer,
 				if (render_audio || (config.enable_audio_scrubbing && audio_scrub)) {
 					if (c->media != nullptr && c->media->get_type() == MEDIA_TYPE_SEQUENCE) {
 						nests.append(c);
-						compose_sequence(viewer, ctx, seq, nests, video, render_audio, gizmos);
+						compose_sequence(viewer, ctx, seq, nests, video, render_audio, gizmos, texture_failed);
 						nests.removeLast();
 					} else {
 						if (c->lock.tryLock()) {
diff --git a/ui/renderfunctions.h b/ui/renderfunctions.h
index 30dcdb853..56af7d3ff 100644
--- a/ui/renderfunctions.h
+++ b/ui/renderfunctions.h
@@ -15,6 +15,6 @@ GLuint compose_sequence(Viewer* viewer,
 						QVector<Clip*>& nests,
 						bool video,
 						bool render_audio,
-						Effect **gizmos);
+						Effect **gizmos, bool &texture_failed);
 
 #endif // RENDERFUNCTIONS_H
diff --git a/ui/renderthread.cpp b/ui/renderthread.cpp
index 81304aa51..66b7d0d55 100644
--- a/ui/renderthread.cpp
+++ b/ui/renderthread.cpp
@@ -10,13 +10,16 @@
 #include "project/sequence.h"
 
 RenderThread::RenderThread() :
-	share_ctx(nullptr),
-	ctx(nullptr),
 	frameBuffer(0),
 	texColorBuffer(0),
+	share_ctx(nullptr),
+	ctx(nullptr),
+	seq(nullptr),
 	tex_width(-1),
 	tex_height(-1),
-	queued(false)
+	queued(false),
+	texture_failed(false),
+	running(true)
 {
 	surface.create();
 }
@@ -28,26 +31,23 @@ RenderThread::~RenderThread() {
 void RenderThread::run() {
 	mutex.lock();
 
-	bool running = true;
-
 	while (running) {
 		if (!queued) {
 			waitCond.wait(&mutex);
 		}
+		if (!running) {
+			break;
+		}
 		queued = false;
 
-		if (share_ctx != nullptr) {
-			if (ctx == nullptr) {
-				ctx = new QOpenGLContext();
-				ctx->setFormat(share_ctx->format());
-				ctx->setShareContext(share_ctx);
-				ctx->create();
-				ctx->makeCurrent(&surface);
-			}
 
+		if (share_ctx != nullptr) {
 			if (ctx != nullptr) {
+				ctx->makeCurrent(&surface);
+
 				// gen fbo
 				if (frameBuffer == 0) {
+					delete_fbo();
 					ctx->functions()->glGenFramebuffers(1, &frameBuffer);
 				}
 
@@ -55,13 +55,8 @@ void RenderThread::run() {
 				ctx->functions()->glBindFramebuffer(GL_DRAW_FRAMEBUFFER, frameBuffer);
 
 				// gen texture
-				if (texColorBuffer == 0 || tex_width != seq->width || tex_height != seq->height) {\
-					if (texColorBuffer > 0) {
-						ctx->functions()->glFramebufferTexture2D(
-							GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, 0, 0
-						);
-						glDeleteTextures(1, &texColorBuffer);
-					}
+				if (texColorBuffer == 0 || tex_width != seq->width || tex_height != seq->height) {
+					delete_texture();
 					glGenTextures(1, &texColorBuffer);
 					glBindTexture(GL_TEXTURE_2D, texColorBuffer);
 					glTexImage2D(
@@ -91,12 +86,7 @@ void RenderThread::run() {
 		}
 	}
 
-	if (ctx != nullptr) {
-		if (texColorBuffer > 0) glDeleteTextures(1, &texColorBuffer);
-		if (frameBuffer > 0) ctx->functions()->glDeleteFramebuffers(1, &frameBuffer);
-		ctx->doneCurrent();
-		delete ctx;
-	}
+	delete_ctx();
 
 	mutex.unlock();
 }
@@ -118,7 +108,7 @@ void RenderThread::paint() {
 	Effect* gizmos; // does nothing yet
 	QVector<Clip*> nests;
 
-	compose_sequence(nullptr, ctx, seq, nests, true, false, &gizmos);
+	compose_sequence(nullptr, ctx, seq, nests, true, false, &gizmos, texture_failed);
 
 	glDisable(GL_DEPTH);
 	glDisable(GL_BLEND);
@@ -126,8 +116,61 @@ void RenderThread::paint() {
 }
 
 void RenderThread::start_render(QOpenGLContext *share, Sequence *s, int idivider) {
-	share_ctx = share;
+	if (s != seq && seq != nullptr) {
+		closeActiveClips(seq);
+	}
+
 	seq = s;
-	queued = true;
+
+	if (share != nullptr && (ctx == nullptr || ctx->shareContext() != share_ctx)) {
+		share_ctx = share;
+		delete_ctx();
+		ctx = new QOpenGLContext();
+		ctx->setFormat(share_ctx->format());
+		ctx->setShareContext(share_ctx);
+		ctx->create();
+		ctx->moveToThread(this);
+	}
+
+	if (seq != nullptr) {
+		queued = true;
+		waitCond.wakeAll();
+	}
+}
+
+bool RenderThread::did_texture_fail() {
+	return texture_failed;
+}
+
+void RenderThread::cancel() {
+	running = false;
 	waitCond.wakeAll();
+	wait();
+}
+
+void RenderThread::delete_texture() {
+	if (texColorBuffer > 0) {
+		ctx->functions()->glFramebufferTexture2D(
+			GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, 0, 0
+		);
+		glDeleteTextures(1, &texColorBuffer);
+	}
+	texColorBuffer = 0;
+}
+
+void RenderThread::delete_fbo() {
+	if (frameBuffer > 0) {
+		ctx->functions()->glDeleteFramebuffers(1, &frameBuffer);
+	}
+	frameBuffer = 0;
+}
+
+void RenderThread::delete_ctx() {
+	if (ctx != nullptr) {
+		delete_texture();
+		delete_fbo();
+		ctx->doneCurrent();
+		delete ctx;
+	}
+	ctx = nullptr;
 }
diff --git a/ui/renderthread.h b/ui/renderthread.h
index e3e1d1def..0bfd2033a 100644
--- a/ui/renderthread.h
+++ b/ui/renderthread.h
@@ -21,9 +21,16 @@ public:
 	GLuint texColorBuffer;
 	void paint();
 	void start_render(QOpenGLContext* share, Sequence* s, int idivider = 0);
+	bool did_texture_fail();
+	void cancel();
 signals:
 	void ready();
 private:
+	// cleanup functions
+	void delete_texture();
+	void delete_fbo();
+	void delete_ctx();
+
 	QWaitCondition waitCond;
 	QOffscreenSurface surface;
 	QOpenGLContext* share_ctx;
@@ -33,6 +40,8 @@ private:
 	int tex_width;
 	int tex_height;
 	bool queued;
+	bool texture_failed;
+	bool running;
 };
 
 #endif // RENDERTHREAD_H
diff --git a/ui/viewercontainer.cpp b/ui/viewercontainer.cpp
index 21f709b1c..15d252f48 100644
--- a/ui/viewercontainer.cpp
+++ b/ui/viewercontainer.cpp
@@ -12,85 +12,85 @@
 
 // enforces aspect ratio
 ViewerContainer::ViewerContainer(QWidget *parent) :
-    QScrollArea(parent),
-    fit(true),
-    child(nullptr)
+	QScrollArea(parent),
+	fit(true),
+	child(nullptr)
 {
-    setFrameShadow(QFrame::Plain);
-    setFrameShape(QFrame::NoFrame);
+	setFrameShadow(QFrame::Plain);
+	setFrameShape(QFrame::NoFrame);
 
-    area = new QWidget(this);
-    area->move(0, 0);
-    setWidget(area);
+	area = new QWidget(this);
+	area->move(0, 0);
+	setWidget(area);
 
-    child = new ViewerWidget(area);
-    child->container = this;
+	child = new ViewerWidget(area);
+	child->container = this;
 }
 
 ViewerContainer::~ViewerContainer() {
-    delete area;
+	delete area;
 }
 
 void ViewerContainer::dragScrollPress(const QPoint &p) {
-    drag_start_x = p.x();
-    drag_start_y = p.y();
-    horiz_start = horizontalScrollBar()->value();
-    vert_start = verticalScrollBar()->value();
+	drag_start_x = p.x();
+	drag_start_y = p.y();
+	horiz_start = horizontalScrollBar()->value();
+	vert_start = verticalScrollBar()->value();
 }
 
 void ViewerContainer::dragScrollMove(const QPoint &p) {
-    int true_x = p.x() + (horiz_start - horizontalScrollBar()->value());
-    int true_y = p.y() + (vert_start - verticalScrollBar()->value());
+	int true_x = p.x() + (horiz_start - horizontalScrollBar()->value());
+	int true_y = p.y() + (vert_start - verticalScrollBar()->value());
 
-    horizontalScrollBar()->setValue(horizontalScrollBar()->value() + (drag_start_x - true_x));
-    verticalScrollBar()->setValue(verticalScrollBar()->value() + (drag_start_y - true_y));
+	horizontalScrollBar()->setValue(horizontalScrollBar()->value() + (drag_start_x - true_x));
+	verticalScrollBar()->setValue(verticalScrollBar()->value() + (drag_start_y - true_y));
 
-    drag_start_x = true_x;
-    drag_start_y = true_y;
+	drag_start_x = true_x;
+	drag_start_y = true_y;
 }
 
 void ViewerContainer::adjust() {
-    if (viewer->seq != nullptr) {
-        if (child->waveform) {
-            child->move(0, 0);
-            child->resize(size());
-        } else if (fit) {
-            double aspect_ratio = double(viewer->seq->width)/double(viewer->seq->height);
+	if (viewer->seq != nullptr) {
+		if (child->waveform) {
+			child->move(0, 0);
+			child->resize(size());
+		} else if (fit) {
+			double aspect_ratio = double(viewer->seq->width)/double(viewer->seq->height);
 
-            int widget_x = 0;
-            int widget_y = 0;
-            int widget_width = width();
-            int widget_height = height();
-            float widget_ar = (float) widget_width /(float) widget_height;
+			int widget_x = 0;
+			int widget_y = 0;
+			int widget_width = width();
+			int widget_height = height();
+			double widget_ar = double(widget_width) / double(widget_height);
 
-            bool widget_is_wider_than_sequence = widget_ar > aspect_ratio;
+			bool widget_is_wider_than_sequence = widget_ar > aspect_ratio;
 
-            if (widget_is_wider_than_sequence) {
-                widget_width = widget_height * aspect_ratio;
-                widget_x = (width() / 2) - (widget_width / 2);
-            } else {
-                widget_height = widget_width / aspect_ratio;
-                widget_y = (height() / 2) - (widget_height / 2);
-            }
+			if (widget_is_wider_than_sequence) {
+				widget_width = widget_height * aspect_ratio;
+				widget_x = (width() / 2) - (widget_width / 2);
+			} else {
+				widget_height = widget_width / aspect_ratio;
+				widget_y = (height() / 2) - (widget_height / 2);
+			}
 
-            child->move(widget_x, widget_y);
-            child->resize(widget_width, widget_height);
+			child->move(widget_x, widget_y);
+			child->resize(widget_width, widget_height);
 
-            zoom = double(widget_width) / double(viewer->seq->width);
-        } else {
-            int zoomed_width = double(viewer->seq->width)*zoom;
-            int zoomed_height = double(viewer->seq->height)*zoom;
-            int zoomed_x = 0;
-            int zoomed_y = 0;
+			zoom = double(widget_width) / double(viewer->seq->width);
+		} else {
+			int zoomed_width = double(viewer->seq->width)*zoom;
+			int zoomed_height = double(viewer->seq->height)*zoom;
+			int zoomed_x = 0;
+			int zoomed_y = 0;
 
-            if (zoomed_width < width()) zoomed_x = (width()>>1)-(zoomed_width>>1);
-            if (zoomed_height < height()) zoomed_y = (height()>>1)-(zoomed_height>>1);
+			if (zoomed_width < width()) zoomed_x = (width()>>1)-(zoomed_width>>1);
+			if (zoomed_height < height()) zoomed_y = (height()>>1)-(zoomed_height>>1);
 
-            child->move(zoomed_x, zoomed_y);
-            child->resize(zoomed_width, zoomed_height);
-        }
+			child->move(zoomed_x, zoomed_y);
+			child->resize(zoomed_width, zoomed_height);
+		}
 	}
-    area->resize(qMax(width(), child->width()), qMax(height(), child->height()));
+	area->resize(qMax(width(), child->width()), qMax(height(), child->height()));
 }
 
 void ViewerContainer::resizeEvent(QResizeEvent *event) {
diff --git a/ui/viewerwidget.cpp b/ui/viewerwidget.cpp
index ae5065696..642d6636e 100644
--- a/ui/viewerwidget.cpp
+++ b/ui/viewerwidget.cpp
@@ -57,7 +57,6 @@ ViewerWidget::ViewerWidget(QWidget *parent) :
 	dragging(false),
 	gizmos(nullptr),
 	selected_gizmo(nullptr),
-	just_repaint(false),
 	window(nullptr)
 {
 	setMouseTracking(true);
@@ -73,6 +72,7 @@ ViewerWidget::ViewerWidget(QWidget *parent) :
 	renderer = new RenderThread();
 	renderer->start(QThread::HighPriority);
 	connect(renderer, SIGNAL(ready()), this, SLOT(queue_repaint()));
+	connect(renderer, SIGNAL(finished()), renderer, SLOT(deleteLater()));
 }
 
 ViewerWidget::~ViewerWidget() {
@@ -80,15 +80,11 @@ ViewerWidget::~ViewerWidget() {
 		window->close();
 		delete window;
 	}
+	renderer->cancel();
 }
 
 void ViewerWidget::delete_function() {
-	// destroy all textures as well
-	if (viewer->seq != nullptr) {
-		makeCurrent();
-		closeActiveClips(viewer->seq);
-		doneCurrent();
-	}
+	renderer->start_render(context(), nullptr);
 }
 
 void ViewerWidget::set_waveform_scroll(int s) {
@@ -173,7 +169,6 @@ void ViewerWidget::save_frame() {
 }
 
 void ViewerWidget::queue_repaint() {
-	just_repaint = true;
 	update();
 }
 
@@ -222,14 +217,10 @@ void ViewerWidget::retry() {
 void ViewerWidget::initializeGL() {
 	initializeOpenGLFunctions();
 
-	connect(context(), SIGNAL(aboutToBeDestroyed()), this, SLOT(delete_function()), Qt::DirectConnection);
-
 	if (window != nullptr) {
 		delete window;
 	}
 	window = new ViewerWindow(context());
-
-//	retry_timer.start();
 }
 
 void ViewerWidget::frame_update() {
@@ -246,7 +237,8 @@ void ViewerWidget::frame_update() {
 
 		// render the audio
 		QVector<Clip*> nests;
-		compose_sequence(viewer, context(), viewer->seq, nests, false, render_audio, &gizmos);
+		bool texture_failed;
+		compose_sequence(viewer, context(), viewer->seq, nests, false, render_audio, &gizmos, texture_failed);
 	}
 }
 
@@ -482,7 +474,7 @@ void ViewerWidget::paintGL() {
 
 		renderer->mutex.unlock();
 
-		if (texture_failed) {
+		if (renderer->did_texture_fail()) {
 			doneCurrent();
 			renderer->start_render(context(), viewer->seq);
 		}
diff --git a/ui/viewerwidget.h b/ui/viewerwidget.h
index dd764101b..8e030bdb2 100644
--- a/ui/viewerwidget.h
+++ b/ui/viewerwidget.h
@@ -28,6 +28,8 @@ public:
 	ViewerWidget(QWidget *parent = 0);
 	~ViewerWidget();
 
+	void delete_function();
+
 	void paintGL();
 	void initializeGL();
 	Viewer* viewer;
@@ -45,11 +47,8 @@ public:
 
 	void frame_update();
 public slots:
-	void delete_function();
 	void set_waveform_scroll(int s);
 protected:
-//	void paintEvent(QPaintEvent *e);
-//    void resizeGL(int w, int h);
 	void mousePressEvent(QMouseEvent *event);
 	void mouseMoveEvent(QMouseEvent *event);
 	void mouseReleaseEvent(QMouseEvent *event);
@@ -68,7 +67,6 @@ private:
 	void move_gizmos(QMouseEvent *event, bool done);
 	RenderThread* renderer;
 	ViewerWindow* window;
-	bool just_repaint;
 private slots:
 	void retry();
 	void show_context_menu();
diff --git a/ui/viewerwindow.cpp b/ui/viewerwindow.cpp
index 3de4ac54e..635cb9491 100644
--- a/ui/viewerwindow.cpp
+++ b/ui/viewerwindow.cpp
@@ -33,8 +33,6 @@ void ViewerWindow::paintGL() {
 		double widget_ar = double(width()) / double(height());
 
 		if (widget_ar > ar) {
-			/*widget_width = widget_height * aspect_ratio;
-			widget_x = (width() / 2) - (widget_width / 2);*/
 			double width = 1.0 * ar / widget_ar;
 			left = (1.0 - width)*0.5;
 			right = left + width;