feat: implement MultiSelectionProp to support grouped object transformation and selection in Viewport

app/gcompose/src/MainPanel.cpp

@@ -13,6 +13,7 @@
 #include <QPushButton>
 #include <QMenu>
 #include <QAction>
+#include <QShortcut>
 #include <QApplication>
 #include <QFileDialog>
 #include <QFileInfo>
@@ -104,6 +105,14 @@ MainPanel::MainPanel(QWidget* parent) : QWidget(parent), m_context(nullptr), m_m
     m_rootSplitter->setSizes(sizes);
 
     mainLayout->addWidget(m_rootSplitter, 1);
+    
+    // Shortcuts
+    auto* groupShortcut = new QShortcut(QKeySequence("Ctrl+G"), this);
+    connect(groupShortcut, &QShortcut::activated, [this]() {
+        if (auto* viewport = qobject_cast<uLib::Vtk::QViewport*>(m_firstPane->currentViewport())) {
+            viewport->GroupSelection(m_context);
+        }
+    });
 }
 
 void MainPanel::setContext(uLib::ObjectsContext* context) {