--- a/src/ui/canvas.h	Sat Feb 29 23:51:03 2020 +0200
+++ b/src/ui/canvas.h	Mon Mar 02 11:08:13 2020 +0200
@@ -24,6 +24,7 @@
 	void selectionChanged(const QSet<ldraw::Id>& newSelection);
 private:
 	void updateGridMatrix();
+	bool isGridPerpendicularToScreen(float threshold) const;
 	std::optional<GridProgram> gridProgram;
 	std::optional<glm::vec3> worldPosition;
 	glm::mat4 gridMatrix;