Set Qt::AA_CompressTabletEvents attribute to avoid latency when scrolling with a tablet

Summary:
BUG: 399208

See also: https://bugreports.qt.io/browse/QTBUG-71708

Enabling this option _vastly_ improves the user experience on wacom tablets and touchscreens

Reviewers: #okular

Subscribers: sander, aacid, okular-devel, #okular

Tags: #okular

Differential Revision: https://phabricator.kde.org/D16519

shell/main.cpp

@@ -31,6 +31,7 @@
 int main(int argc, char** argv)
 {
     QGuiApplication::setAttribute(Qt::AA_UseHighDpiPixmaps);
+    QCoreApplication::setAttribute(Qt::AA_CompressTabletEvents);
 
     QApplication app(argc, argv);
     KLocalizedString::setApplicationDomain("okular");