Assign parent directly. Remove setLayout(...) when not necessary

src/filter/filteractions/filteractionwidget.cpp

@@ -109,9 +109,8 @@ FilterActionWidget::FilterActionWidget(QWidget *parent)
     : QWidget(parent)
     , d(new Private(this))
 {
-    QHBoxLayout *mainLayout = new QHBoxLayout;
+    QHBoxLayout *mainLayout = new QHBoxLayout(this);
     mainLayout->setMargin(0);
-    setLayout(mainLayout);
     QWidget *widget = new QWidget(this);
     mainLayout->addWidget(widget);
 

src/filter/tests/filterimporterexportergui.cpp

@@ -29,8 +29,7 @@ Q_DECLARE_METATYPE(MailCommon::FilterImporterExporter::FilterType)
 FilterImporterExporterGui::FilterImporterExporterGui(QWidget *parent)
     : QWidget(parent)
 {
-    QVBoxLayout *mainLayout = new QVBoxLayout;
-    setLayout(mainLayout);
+    QVBoxLayout *mainLayout = new QVBoxLayout(this);
     QMenuBar *menuBar = new QMenuBar(this);
     mainLayout->addWidget(menuBar);
     QMenu *menuFilter = menuBar->addMenu(QStringLiteral("filter"));

src/folder/folderselectiondialog.cpp

@@ -68,8 +68,7 @@ FolderSelectionDialog::FolderSelectionDialog(QWidget *parent, SelectionFolderOpt
 
     d->mNotAllowToCreateNewFolder = (options & FolderSelectionDialog::NotAllowToCreateNewFolder);
     QDialogButtonBox *buttonBox = new QDialogButtonBox(QDialogButtonBox::Ok | QDialogButtonBox::Cancel, this);
-    QVBoxLayout *mainLayout = new QVBoxLayout;
-    setLayout(mainLayout);
+    QVBoxLayout *mainLayout = new QVBoxLayout(this);
     d->mOkButton = buttonBox->button(QDialogButtonBox::Ok);
     d->mOkButton->setDefault(true);
     d->mOkButton->setAutoDefault(true);