Merge #580: Getting ready to Qt 6 (3/n). Do not use QKeyEvent copy constructor

3ec6504 qt: Do not use `QKeyEvent` copy constructor (Hennadii Stepanov)

Pull request description:

  This PR is preparation for [Qt 6](bitcoin/bitcoin#24798), and it fixes an experimental build with Qt 6.2.4 as copying of `QEvent` has been [disabled](qt/qtbase@19f9b0d) in Qt 6.0.0.

ACKs for top commit:
  w0xlt:
    tACK 3ec6504 on Ubuntu 21.10, Qt 5.15.2
  shaavan:
    reACK 3ec6504

Tree-SHA512: 583a9dad0c621d9f02f77ccaa9f55ee79e12e3c47f418911ef2dfe0de357d772d1928ae3ec19b6f0c0674da858bab9d4542a26cc14b06ed921370dfeabd1c194

Author: hebasto

src/qt/rpcconsole.cpp

@@ -618,17 +618,16 @@ bool RPCConsole::eventFilter(QObject* obj, QEvent *event)
         case Qt::Key_Down: if(obj == ui->lineEdit) { browseHistory(1); return true; } break;
         case Qt::Key_PageUp: /* pass paging keys to messages widget */
         case Qt::Key_PageDown:
-            if(obj == ui->lineEdit)
-            {
-                QApplication::postEvent(ui->messagesWidget, new QKeyEvent(*keyevt));
+            if (obj == ui->lineEdit) {
+                QApplication::sendEvent(ui->messagesWidget, keyevt);
                 return true;
             }
             break;
         case Qt::Key_Return:
         case Qt::Key_Enter:
             // forward these events to lineEdit
-            if(obj == autoCompleter->popup()) {
-                QApplication::postEvent(ui->lineEdit, new QKeyEvent(*keyevt));
+            if (obj == autoCompleter->popup()) {
+                QApplication::sendEvent(ui->lineEdit, keyevt);
                 autoCompleter->popup()->hide();
                 return true;
             }
@@ -642,7 +641,7 @@ bool RPCConsole::eventFilter(QObject* obj, QEvent *event)
                   ((mod & Qt::ShiftModifier) && key == Qt::Key_Insert)))
             {
                 ui->lineEdit->setFocus();
-                QApplication::postEvent(ui->lineEdit, new QKeyEvent(*keyevt));
+                QApplication::sendEvent(ui->lineEdit, keyevt);
                 return true;
             }
         }