Ignore horizontal wheel scrolling in workarea

We do not know what to do with horizontal scrolling events, so we ignore them.

Note that the code has to be different between Qt4 and Qt5.

Fixes bug #11257.

(cherry picked from commit 2cfbc5ecf6)

src/frontends/qt4/GuiWorkArea.cpp

@@ -897,7 +897,23 @@ void GuiWorkArea::wheelEvent(QWheelEvent * ev)
 {
 	// Wheel rotation by one notch results in a delta() of 120 (see
 	// documentation of QWheelEvent)
+	// But first we have to ignore horizontal scroll events.
+#if QT_VERSION < 0x050000
+	if (ev->orientation() == Qt::Horizontal) {
+		ev->accept();
+		return;
+	}
 	double const delta = ev->delta() / 120.0;
+#else
+	QPoint const aDelta = ev->angleDelta();
+	// skip horizontal wheel event
+	if (abs(aDelta.x()) > abs(aDelta.y())) {
+		ev->accept();
+		return;
+	}
+	double const delta = aDelta.y() / 120.0;
+#endif
+
 	bool zoom = false;
 	switch (lyxrc.scroll_wheel_zoom) {
 	case LyXRC::SCROLL_WHEEL_ZOOM_CTRL:

status.23x

@@ -106,6 +106,8 @@ What's new
 
 - Fix conversion of captions from LyX 2.0 documents.
 
+- Ignore horizontal wheel scrolling in work area (bug 11257).
+
 
 
 * USER INTERFACE