diff --git a/fixtracks/centralwidget.py b/fixtracks/centralwidget.py
index 2858499..8b9a5e6 100644
--- a/fixtracks/centralwidget.py
+++ b/fixtracks/centralwidget.py
@@ -1,5 +1,6 @@
 import logging
 from PyQt6.QtWidgets import QWidget, QStackedLayout
+from PyQt6.QtCore import Qt
 
 from fixtracks.taskwidgets import FixTracks
 from fixtracks.detectionmerge import MergeDetections
@@ -10,7 +11,9 @@ class CentralWidget(QWidget):
     def __init__(self, parent=None):
         super().__init__(parent)
         layout = QStackedLayout()
+        layout.setAlignment(Qt.AlignmentFlag.AlignVCenter)
         self._tw = TasksWidget()
+        self._tw.setMaximumHeight(200)
         self._tw.clicked.connect(self._select_task)
         self._tasksindex = layout.addWidget(self._tw)
         self._mergewidget = MergeDetections(self)
diff --git a/fixtracks/detectionmerge.py b/fixtracks/detectionmerge.py
index 38204a2..697f5c3 100644
--- a/fixtracks/detectionmerge.py
+++ b/fixtracks/detectionmerge.py
@@ -8,14 +8,15 @@ from fixtracks.util import ImageReader
 
 
 class VideoPreview(QWidget):
-    def __init__(self, parent=None):
-        super().__init__(parent)
+    def __init__(self, left=True, parent=None):
+        super().__init__(None)
         self._image  = None
         self._line_pen = QPen(QColor.fromString("red"), 4)  
         self._view = QGraphicsView()
         self._view.setSizePolicy(QSizePolicy.Policy.Expanding, QSizePolicy.Policy.Expanding)
         self._scene = None
         self._pixmap = None
+        self._left = left
         layout = QVBoxLayout()
         layout.addWidget(self._view)
         self.setLayout(layout)
@@ -26,7 +27,7 @@ class VideoPreview(QWidget):
         self._view.setScene(self._scene)
         self._view.fitInView(self._scene.sceneRect(), mode=Qt.AspectRatioMode.KeepAspectRatio)
         image_rect = self._pixmap.boundingRect()
-        start_x = image_rect.right() 
+        start_x = image_rect.right() if self._left else image_rect.left()
         start_y = image_rect.top()
         end_y = image_rect.bottom()
 
@@ -62,7 +63,7 @@ class MergeDetections(QWidget):
         self.left_videocombo.addItems(self._files)
         self.left_posspinner = QSpinBox()
         self.left_posspinner.valueChanged.connect(self.on_leftmergelinemove)
-        self.left_preview = VideoPreview(self)
+        self.left_preview = VideoPreview()
         
         self.right_datacombo = QComboBox()
         self.right_videocombo = QComboBox()
@@ -70,7 +71,7 @@ class MergeDetections(QWidget):
         self.right_videocombo.addItems(self._files)
         self.right_posspinner = QSpinBox()
         self.right_posspinner.valueChanged.connect(self.on_rightmergelinemove)
-        self.right_preview = VideoPreview(self)
+        self.right_preview = VideoPreview(left=False)
 
         layout.addLayout(self.layout_controls())
         splitter = QGridLayout()
@@ -106,7 +107,6 @@ class MergeDetections(QWidget):
         grd.setColumnStretch(3, 50)
         grd.setColumnMinimumWidth(0, 50)
         grd.setColumnMinimumWidth(2, 50)
-        # grd.setRowStretch(4, 100)
         return grd
 
     @property
@@ -138,13 +138,11 @@ class MergeDetections(QWidget):
         self.right_datacombo.setCurrentIndex(0)
         self.right_videocombo.currentIndexChanged.connect(self.on_rightvideoSelection)
         self.left_videocombo.currentIndexChanged.connect(self.on_leftvideoSelection)
-        # self._files = file_list
 
     def _toImage(self, frame):
         height, width, _ = frame.shape
         bytesPerLine = 3 * width
         img = QImage(frame.data, width, height, bytesPerLine, QImage.Format.Format_BGR888).rgbSwapped()
-        # pm = QPixmap.fromImage(img)
         return img
         
     def on_rightvideoSelection(self):
@@ -159,7 +157,7 @@ class MergeDetections(QWidget):
         img = self._toImage(frame)
         self.right_preview.set_image(img)
         self.right_posspinner.setMaximum(img.width() - 1)
-        self.right_posspinner.setValue(img.width() - 1)
+        self.right_posspinner.setValue(0)
 
     def on_leftvideoSelection(self):
         logging.debug("Video selection of the %s side", "left")
@@ -178,5 +176,5 @@ class MergeDetections(QWidget):
     def on_leftmergelinemove(self):
         self.left_preview.set_lineposition(self.left_posspinner.value())
 
-    def on_leftmergelinemove(self):
+    def on_rightmergelinemove(self):
         self.right_preview.set_lineposition(self.right_posspinner.value())
diff --git a/fixtracks/taskwidget.py b/fixtracks/taskwidget.py
index 167cb70..a967355 100644
--- a/fixtracks/taskwidget.py
+++ b/fixtracks/taskwidget.py
@@ -1,8 +1,8 @@
 import logging
 import pathlib
 
-from PyQt6.QtWidgets import QWidget, QVBoxLayout, QLabel, QPushButton, QFileDialog
-from PyQt6.QtCore import pyqtSignal
+from PyQt6.QtWidgets import QWidget, QHBoxLayout, QVBoxLayout, QLabel, QPushButton, QFileDialog, QSizePolicy
+from PyQt6.QtCore import pyqtSignal, Qt
 
 
 class TasksWidget(QWidget):
@@ -10,20 +10,28 @@ class TasksWidget(QWidget):
 
     def __init__(self, parent = None):
         super().__init__(parent)
-        l = QVBoxLayout()
-        l.addWidget(QLabel("Tasks:"))
+        l = QHBoxLayout()
+        l.setAlignment(Qt.AlignmentFlag.AlignVCenter)
         folderBtn = QPushButton("Select data folder")
         folderBtn.setEnabled(True)
+        folderBtn.setSizePolicy(QSizePolicy.Policy.Expanding, QSizePolicy.Policy.Expanding)
         folderBtn.clicked.connect(self._open_folder)
         l.addWidget(folderBtn)
+
+        sublayout = QVBoxLayout()
         self.mergeBtn = QPushButton("Merge detections")
         self.mergeBtn.setEnabled(False)
         self.mergeBtn.clicked.connect(self._merge_clicked)
+        self.mergeBtn.setSizePolicy(QSizePolicy.Policy.Expanding, QSizePolicy.Policy.Expanding)
+
         self.tracksBtn = QPushButton("Join tracks")
         self.tracksBtn.setEnabled(False)
         self.tracksBtn.clicked.connect(self._tracks_clicked)
-        l.addWidget(self.mergeBtn)
-        l.addWidget(self.tracksBtn)
+        self.tracksBtn.setSizePolicy(QSizePolicy.Policy.Expanding, QSizePolicy.Policy.Expanding)
+
+        sublayout.addWidget(self.mergeBtn)
+        sublayout.addWidget(self.tracksBtn)
+        l.addLayout(sublayout)
         self.setLayout(l)
         self._file_list = []