diff --git a/effects/effects.h b/effects/effects.h
index aae488b71..fbd8f51e7 100644
--- a/effects/effects.h
+++ b/effects/effects.h
@@ -29,7 +29,7 @@ class TransformEffect : public Effect {
 public:
     TransformEffect(Clip* c);
 	void process_gl(int* anchor_x, int* anchor_y);
-    Effect* copy();
+    Effect* copy(Clip* c);
 
 	QSpinBox* position_x;
 	QSpinBox* position_y;
@@ -52,7 +52,7 @@ class VolumeEffect : public Effect {
 public:
     VolumeEffect(Clip* c);
     void process_audio(uint8_t* samples, int nb_bytes);
-    Effect* copy();
+    Effect* copy(Clip* c);
     void load(QXmlStreamReader* stream);
     void save(QXmlStreamWriter* stream);
 
@@ -63,7 +63,7 @@ class PanEffect : public Effect {
 public:
     PanEffect(Clip* c);
     void process_audio(uint8_t* samples, int nb_bytes);
-    Effect* copy();
+    Effect* copy(Clip* c);
     void load(QXmlStreamReader* stream);
     void save(QXmlStreamWriter* stream);
 
diff --git a/effects/paneffect.cpp b/effects/paneffect.cpp
index d99a8c1e8..3d957a2f3 100644
--- a/effects/paneffect.cpp
+++ b/effects/paneffect.cpp
@@ -25,8 +25,8 @@ PanEffect::PanEffect(Clip* c) : Effect(c) {
 	pan_val->setValue(0);
 }
 
-Effect* PanEffect::copy() {
-    PanEffect* p = new PanEffect(parent_clip);
+Effect* PanEffect::copy(Clip* c) {
+    PanEffect* p = new PanEffect(c);
     p->pan_val->setValue(pan_val->value());
     return p;
 }
diff --git a/effects/transformeffect.cpp b/effects/transformeffect.cpp
index 6023e8d40..d9a724e24 100644
--- a/effects/transformeffect.cpp
+++ b/effects/transformeffect.cpp
@@ -93,8 +93,8 @@ TransformEffect::TransformEffect(Clip* c) : Effect(c) {
 	connect(uniform_scale_box, SIGNAL(toggled(bool)), this, SLOT(field_changed()));
 }
 
-Effect* TransformEffect::copy() {
-    TransformEffect* t = new TransformEffect(parent_clip);
+Effect* TransformEffect::copy(Clip* c) {
+    TransformEffect* t = new TransformEffect(c);
     t->position_x->setValue(position_x->value());
     t->position_y->setValue(position_y->value());
     t->scale_x->setValue(scale_x->value());
diff --git a/effects/volumeeffect.cpp b/effects/volumeeffect.cpp
index 08a0e8da9..6826eb0f3 100644
--- a/effects/volumeeffect.cpp
+++ b/effects/volumeeffect.cpp
@@ -25,8 +25,8 @@ VolumeEffect::VolumeEffect(Clip* c) : Effect(c) {
 	volume_val->setValue(100);
 }
 
-Effect* VolumeEffect::copy() {
-    VolumeEffect* v = new VolumeEffect(parent_clip);
+Effect* VolumeEffect::copy(Clip* c) {
+    VolumeEffect* v = new VolumeEffect(c);
     v->volume_val->setValue(volume_val->value());
     return v;
 }
diff --git a/io/previewgenerator.cpp b/io/previewgenerator.cpp
index 843196fbb..c8fe936c0 100644
--- a/io/previewgenerator.cpp
+++ b/io/previewgenerator.cpp
@@ -1,6 +1,6 @@
 #include "previewgenerator.h"
 
-PreviewGenerator::PreviewGenerator(QWidget* parent) : QThread(parent)
+PreviewGenerator::PreviewGenerator(QObject* parent) : QThread(parent)
 {
 
 }
diff --git a/io/previewgenerator.h b/io/previewgenerator.h
index e3c256a15..e13447443 100644
--- a/io/previewgenerator.h
+++ b/io/previewgenerator.h
@@ -6,7 +6,7 @@
 class PreviewGenerator : public QThread
 {
 public:
-    PreviewGenerator(QWidget* parent = 0);
+    PreviewGenerator(QObject* parent = 0);
     void run() override;
 };
 
diff --git a/olive.pro.user b/olive.pro.user
index 25e111309..d57c157b8 100644
--- a/olive.pro.user
+++ b/olive.pro.user
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!DOCTYPE QtCreatorProject>
-<!-- Written by QtCreator 4.6.1, 2018-06-13T22:15:23. -->
+<!-- Written by QtCreator 4.6.1, 2018-06-13T17:04:15. -->
 <qtcreator>
  <data>
   <variable>EnvironmentId</variable>
diff --git a/panels/timeline.cpp b/panels/timeline.cpp
index c7c3415c4..5d4fe19c7 100644
--- a/panels/timeline.cpp
+++ b/panels/timeline.cpp
@@ -164,8 +164,8 @@ void Timeline::redraw_all_clips() {
     sequence->undo_add_current();
     project_changed = true;
 
-	ui->video_area->redraw_clips();
-	ui->audio_area->redraw_clips();
+    ui->video_area->redraw_clips();
+    ui->audio_area->redraw_clips();
 }
 
 void Timeline::select_all() {
diff --git a/project/clip.cpp b/project/clip.cpp
index de4404704..6797fec71 100644
--- a/project/clip.cpp
+++ b/project/clip.cpp
@@ -18,7 +18,7 @@ Clip::Clip() {
 Clip* Clip::copy() {
     Clip* copy = new Clip();
 
-    copy->name = name;
+    copy->name = QString(name);
     copy->clip_in = clip_in;
     copy->timeline_in = timeline_in;
     copy->timeline_out = timeline_out;
@@ -31,7 +31,7 @@ Clip* Clip::copy() {
     copy->media_stream = media_stream;
 
     for (int i=0;i<effects.size();i++) {
-        copy->effects.append(effects.at(i)->copy());
+        copy->effects.append(effects.at(i)->copy(copy));
     }
 
     return copy;
diff --git a/project/clip.h b/project/clip.h
index f8418333e..932cd580b 100644
--- a/project/clip.h
+++ b/project/clip.h
@@ -20,7 +20,6 @@ struct AVPacket;
 struct SwsContext;
 struct SwrContext;
 class QOpenGLTexture;
-class QPixmap;
 
 struct ClipCache {
 	AVFrame** frames;
@@ -50,7 +49,7 @@ struct Clip
 	uint8_t color_b;
 	long getLength();
 
-	// inherited information (should be copied in copy())
+    // inherited information (should be set to the same references in copy())
 	Media* media; // attached media
 	MediaStream* media_stream;
 	Sequence* sequence;
diff --git a/project/effect.cpp b/project/effect.cpp
index 68a928772..8c6caa2f5 100644
--- a/project/effect.cpp
+++ b/project/effect.cpp
@@ -28,9 +28,9 @@ void Effect::field_changed() {
 	panel_viewer->viewer_widget->update();
 }
 
-Effect* Effect::copy() {return NULL;}
-void Effect::load(QXmlStreamReader* stream) {}
-void Effect::save(QXmlStreamWriter *stream) {}
+Effect* Effect::copy(Clip*) {return NULL;}
+void Effect::load(QXmlStreamReader*) {}
+void Effect::save(QXmlStreamWriter*) {}
 
 void Effect::process_gl(int*, int*) {}
 void Effect::process_audio(uint8_t*, int) {}
diff --git a/project/effect.h b/project/effect.h
index c7e67b80a..c29488862 100644
--- a/project/effect.h
+++ b/project/effect.h
@@ -24,7 +24,7 @@ public:
 	QWidget* ui;
     Clip* parent_clip;
 
-    virtual Effect* copy();
+    virtual Effect* copy(Clip* c);
     virtual void load(QXmlStreamReader* stream);
     virtual void save(QXmlStreamWriter* stream);
 
diff --git a/project/sequence.cpp b/project/sequence.cpp
index 32b76c1aa..813f01a73 100644
--- a/project/sequence.cpp
+++ b/project/sequence.cpp
@@ -95,8 +95,8 @@ void Sequence::undo_add_current() {
         undo_stack.removeFirst();
     } else {
         undo_pointer++;
-        for (int i=undo_stack.size()-1;i>undo_pointer;i--) {
-            delete undo_stack[i];
+        while (undo_stack.size() > undo_pointer+1) {
+            delete undo_stack.last();
             undo_stack.removeLast();
         }
     }
@@ -115,9 +115,9 @@ void Sequence::set_undo(int i) {
     }
     clips.clear();
 
-    QVector<Clip*>* copy_from_list = undo_stack[undo_pointer];
+    QVector<Clip*>* copy_from_list = undo_stack.at(undo_pointer);
     for (int i=0;i<copy_from_list->size();i++) {
-        add_clip(copy_from_list->at(i));
+        add_clip(copy_from_list->at(i)->copy());
     }
 }
 
diff --git a/ui/timelinewidget.cpp b/ui/timelinewidget.cpp
index 02332f606..ff04129f7 100644
--- a/ui/timelinewidget.cpp
+++ b/ui/timelinewidget.cpp
@@ -761,26 +761,26 @@ void TimelineWidget::redraw_clips() {
                 video_track_limit = clip->track;
             } else if (clip->track > audio_track_limit) {
                 audio_track_limit = clip->track;
-			}
+            }
 
             QRect clip_rect(panel_timeline->getScreenPointFromFrame(clip->timeline_in), getScreenPointFromTrack(clip->track), clip->getLength() * panel_timeline->zoom, track_height);
             clip_painter.fillRect(clip_rect, QColor(clip->color_r, clip->color_g, clip->color_b));
-			clip_painter.setPen(Qt::white);
-			clip_painter.drawLine(clip_rect.bottomLeft(), clip_rect.topLeft());
-			clip_painter.drawLine(clip_rect.topLeft(), clip_rect.topRight());
+            clip_painter.setPen(Qt::white);
+            clip_painter.drawLine(clip_rect.bottomLeft(), clip_rect.topLeft());
+            clip_painter.drawLine(clip_rect.topLeft(), clip_rect.topRight());
             clip_painter.setPen(Qt::gray);
-			clip_painter.drawLine(clip_rect.bottomLeft(), clip_rect.bottomRight());
-			clip_painter.drawLine(clip_rect.bottomRight(), clip_rect.topRight());
+            clip_painter.drawLine(clip_rect.bottomLeft(), clip_rect.bottomRight());
+            clip_painter.drawLine(clip_rect.bottomRight(), clip_rect.topRight());
 
             if (color_brightness(clip->color_r, clip->color_g, clip->color_b) > 160) {
-				clip_painter.setPen(Qt::black);
-			} else {
-				clip_painter.setPen(Qt::white);
-			}
-			QRect text_rect(clip_rect.left() + CLIP_TEXT_PADDING, clip_rect.top() + CLIP_TEXT_PADDING, clip_rect.width() - CLIP_TEXT_PADDING - CLIP_TEXT_PADDING, clip_rect.height() - CLIP_TEXT_PADDING - CLIP_TEXT_PADDING);
+                clip_painter.setPen(Qt::black);
+            } else {
+                clip_painter.setPen(Qt::white);
+            }
+            QRect text_rect(clip_rect.left() + CLIP_TEXT_PADDING, clip_rect.top() + CLIP_TEXT_PADDING, clip_rect.width() - CLIP_TEXT_PADDING - CLIP_TEXT_PADDING, clip_rect.height() - CLIP_TEXT_PADDING - CLIP_TEXT_PADDING);
             clip_painter.drawText(text_rect, 0, clip->name, &text_rect);
-		}
-	}
+        }
+    }
 
 	// Draw track lines
 	if (show_track_lines) {