GUI: allow delete key to remove entries from string list configuration widgets

See #3585

NEWS.md

@@ -9,6 +9,9 @@
   properties has been changed: the old element is now titled "Language
   (obsolete)" & the current, IETF BCP 47 based one is simply called
   "Language".
+* MKVToolNix GUI: preferences: you can now use the "delete" key to remove
+  entries from simple list widgets for strings (e.g. the list of recently used
+  destination directories).
 
 ## Bug fixes
 

src/mkvtoolnix-gui/util/string_list_configuration_widget.cpp

@@ -2,6 +2,8 @@
 
 #include <QDir>
 #include <QInputDialog>
+#include <QKeyEvent>
+#include <QKeySequence>
 #include <QListWidget>
 #include <QPushButton>
 #include <QRegularExpression>
@@ -35,6 +37,8 @@ StringListConfigurationWidget::StringListConfigurationWidget(QWidget *parent)
 
   p->ui->pbRemoveItem->setEnabled(false);
 
+  p->ui->lwItems->installEventFilter(this);
+
   setupConnections();
 }
 
@@ -161,4 +165,19 @@ StringListConfigurationWidget::setItemType(ItemType itemType) {
   p_func()->itemType = itemType;
 }
 
+bool
+StringListConfigurationWidget::eventFilter(QObject *o,
+                                           QEvent *e) {
+  auto p = p_func();
+
+  if (   (o           == p->ui->lwItems)
+      && (e->type()   == QEvent::KeyPress)
+      && (static_cast<QKeyEvent *>(e)->matches(QKeySequence::Delete))) {
+    removeSelectedItems();
+    return true;
+  }
+
+  return QWidget::eventFilter(o, e);
+}
+
 }

src/mkvtoolnix-gui/util/string_list_configuration_widget.h

@@ -2,6 +2,7 @@
 
 #include "common/common_pch.h"
 
+#include <QEvent>
 #include <QList>
 #include <QStringList>
 #include <QWidget>
@@ -47,6 +48,8 @@ public:
 
   void addItem(QString const &name);
 
+  virtual bool eventFilter(QObject *o, QEvent *e) override;
+
 public Q_SLOTS:
   void enableControls();