tdf#122238 KDE5: disable mechanism of Qt for shortcut activation

When QEvent::KeyPress event is processed, QEvent::ShortcutOverride event is created
and processed before finishing processing original event.

If it's an active shortcut, and QEvent::ShortcutOverride event is not accepted,
the shortcut is activated, but QEvent::KeyPress event is omitted.
If it's an active shortcut, and QEvent::ShortcutOverride event is accepted,
the shortcut is not activated, and QEvent::KeyPress event is sent as usual.

But it looks like even if shortcut activation is suppressed,
shortcut is still called somewhere from insides SalEvent::KeyInput
event processing callback from Qt5Widget::handleKeyEvent function.

Shortcuts are still assigned to menu actions
since it shows the key combinations used to activate them.

Change-Id: I1ffc63c2530dd61ae67ab66a96ea3efe767218c0
Reviewed-on: https://gerrit.libreoffice.org/66444
Tested-by: Jenkins
Reviewed-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>

vcl/inc/qt5/Qt5Widget.hxx

@@ -45,6 +45,8 @@ class Qt5Widget : public QWidget
     bool handleKeyEvent(QKeyEvent*, bool);
     void handleMouseButtonEvent(QMouseEvent*, bool);
 
+    virtual bool event(QEvent*) override;
+
     virtual void focusInEvent(QFocusEvent*) override;
     virtual void focusOutEvent(QFocusEvent*) override;
     virtual void keyPressEvent(QKeyEvent*) override;

vcl/qt5/Qt5Widget.cxx

@@ -395,6 +395,22 @@ bool Qt5Widget::handleKeyEvent(QKeyEvent* pEvent, bool bDown)
     return bStopProcessingKey;
 }
 
+bool Qt5Widget::event(QEvent* pEvent)
+{
+    if (pEvent->type() == QEvent::ShortcutOverride)
+    {
+        // Accepted event disables shortcut activation,
+        // but enables keypress event.
+        // If event is not accepted and shortcut is successfully activated,
+        // KeyPress event is omitted.
+        // It looks like handleKeyEvent function still activates the shortcut on KeyPress event,
+        // so there's no harm in disabling shortcut activation via Qt mechanisms.
+        pEvent->accept();
+    }
+
+    return QWidget::event(pEvent);
+}
+
 void Qt5Widget::keyPressEvent(QKeyEvent* pEvent)
 {
     if (handleKeyEvent(pEvent, true))