diff -r 0f80a2e5e42b -r 1a9eac27698d src/ui/canvas.h
--- a/src/ui/canvas.h	Fri Feb 07 02:02:16 2020 +0200
+++ b/src/ui/canvas.h	Fri Feb 07 23:59:06 2020 +0200
@@ -10,8 +10,17 @@
 		DocumentManager* documents,
 		const ldraw::ColorTable& colorTable,
 		QWidget* parent = nullptr);
+public slots:
+	void handleSelectionChange(const QSet<ldraw::Id>& selectedIds, const QSet<ldraw::Id>& deselectedIds);
 protected:
 	void mouseMoveEvent(QMouseEvent* event) override;
+	void mousePressEvent(QMouseEvent* event) override;
+	void mouseReleaseEvent(QMouseEvent* event) override;
 signals:
 	void newStatusText(const QString& newStatusText);
+	void selectionChanged(const QSet<ldraw::Id>& newSelection);
+private:
+	QPoint lastMousePosition;
+	int totalMouseMove = 0;
+	QSet<ldraw::Id> selection;
 };