QGtkWindow: Display all popup-type windows as popups

Qt::WindowType is a flags type, and there are multiple window types that
include Qt::Popup. All of these should be displayed as popup windows.

This fixes certain window types stealing focus or displaying incorrectly.

src/qgtkwindow.cpp

@@ -170,8 +170,7 @@ void QGtkWindow::create(Qt::WindowType windowType)
 
     // Determine the window type. GTK_WINDOW_TOPLEVEL is usually right.
     GtkWindowType gtkWindowType = GTK_WINDOW_TOPLEVEL;
-    if (windowType == Qt::ToolTip ||
-        windowType == Qt::Popup) {
+    if ((windowType & Qt::Popup) == Qt::Popup) {
         gtkWindowType = GTK_WINDOW_POPUP;
     }