Add missing parent pointer to few QMessageBox and QFontDialog (#3679)

Co-authored-by: Felanbird <41973452+Felanbird@users.noreply.github.com>
Co-authored-by: pajlada <rasmus.karlsson@pajlada.com>

src/widgets/Notebook.cpp

@@ -368,7 +368,7 @@ void Notebook::setShowTabs(bool value)
     // show a popup upon hiding tabs
     if (!value && getSettings()->informOnTabVisibilityToggle.getValue())
     {
-        QMessageBox msgBox;
+        QMessageBox msgBox(this->window());
         msgBox.window()->setWindowTitle("Chatterino - hidden tabs");
         msgBox.setText("You've just hidden your tabs.");
         msgBox.setInformativeText(

src/widgets/settingspages/FiltersPage.cpp

@@ -88,7 +88,7 @@ void FiltersPage::tableCellClicked(const QModelIndex &clicked,
     // valid column
     if (clicked.column() == 2)
     {
-        QMessageBox popup;
+        QMessageBox popup(this->window());
 
         filterparser::FilterParser f(
             view->getModel()->data(clicked.siblingAtColumn(1)).toString());

src/widgets/settingspages/GeneralPage.cpp

@@ -735,10 +735,8 @@ QString GeneralPage::getFont(const DropdownArgs &args) const
         args.combobox->setEditText("Choosing...");
         QFontDialog dialog(getApp()->fonts->getFont(FontStyle::ChatMedium, 1.));
 
-        dialog.setWindowFlag(Qt::WindowStaysOnTopHint);
-
         auto ok = bool();
-        auto font = dialog.getFont(&ok);
+        auto font = dialog.getFont(&ok, this->window());
 
         if (ok)
             return font.family();

src/widgets/splits/Split.cpp

@@ -219,7 +219,7 @@ Split::Split(QWidget *parent)
 
             if (getSettings()->askOnImageUpload.getValue())
             {
-                QMessageBox msgBox;
+                QMessageBox msgBox(this->window());
                 msgBox.setWindowTitle("Chatterino");
                 msgBox.setText("Image upload");
                 msgBox.setInformativeText(