backported fix to qt5.5

mainwindow.cpp

@@ -63,9 +63,7 @@ void MainWindow::setup_layout() {
 	addDockWidget(Qt::BottomDockWidgetArea, panel_timeline);
 
 	// workaround for older versions of Qt (but not too old)
-#if QT_VERSION >= QT_VERSION_CHECK(5, 6, 0) // adds compatibility with 5.5
-	resizeDocks({panel_project}, {40}, Qt::Horizontal);
-#endif
+	layout()->update();
 }
 
 MainWindow::MainWindow(QWidget *parent) :
@@ -107,6 +105,8 @@ MainWindow::MainWindow(QWidget *parent) :
 
     setDockNestingEnabled(true);
 
+	layout()->invalidate();
+
     // TODO maybe replace these with non-pointers later on?
     panel_sequence_viewer = new Viewer(this);
 	panel_footage_viewer = new Viewer(this);