draw rounded rectangle using thickness radius instead of drawing simple rectangle

src/tools/rectangle/rectangletool.cpp

@@ -62,7 +62,7 @@ void RectangleTool::process(QPainter& painter,
     }
     painter.setPen(QPen(m_color, m_thickness));
     painter.setBrush(QBrush(m_color));
-    painter.drawRect(QRect(m_points.first, m_points.second));
+    painter.drawRoundedRect(QRect(m_points.first, m_points.second), m_thickness, m_thickness);
 }
 
 void RectangleTool::paintMousePreview(QPainter& painter,