Install middle click event handler on KXmlGui Toolbar menu

For ease of access, KXmlGui adds actions in a delayed/split toolbar
button to its own context menu. We have no access to this menu, so
we cannot install our middle-click event handler for the back/forward
action menus.

To address this, we detect the action showing for the first time and
install an event filter on the associated object if we think it's
the menu.

1 files changed, 18 insertions, 0 deletions

diff --git a/src/middleclickactioneventfilter.cpp b/src/middleclickactioneventfilter.cpp
index 7f98e727e..2d943475a 100644
--- a/src/middleclickactioneventfilter.cpp
+++ b/src/middleclickactioneventfilter.cpp
@@ -7,6 +7,7 @@
 #include "middleclickactioneventfilter.h"
 
 #include <QAction>
+#include <QActionEvent>
 #include <QEvent>
 #include <QMenu>
 #include <QMouseEvent>
@@ -55,6 +56,23 @@ bool MiddleClickActionEventFilter::eventFilter(QObject *watched, QEvent *event)
                 }
             }
         }
+
+    } else if (event->type() == QEvent::ActionChanged) {
+        // KXmlGui adds delayed popup menu's actions to its own context menu.
+        // In order for middle click to work, we need to somehow detect when the action is added
+        // on this menu and install the event filter on it.
+        // Visibility of the action changes when the menu shows in the menu for the first time,
+        // so we'll receive an ActionChanged event and use that.
+        auto *actionEvent = static_cast<QActionEvent *>(event);
+
+        const auto items = actionEvent->action()->associatedObjects();
+        for (auto *item : items) {
+            if (auto *menu = qobject_cast<QMenu *>(item)) {
+                if (menu != actionEvent->action()->parent()) { // Parent is the regular menu.
+                    menu->installEventFilter(this);
+                }
+            }
+        }
     }
 
     return QObject::eventFilter(watched, event);