+<li>To add the same size on several geometries, multi-selection is possible.</li>
+<li>The sizes are either constant values or python functions.</li>
+<li>In the case of a python function, the following rules must be respected:
+<ul>
+<li>The name of the function is f</li>
+<li>If geometry is face or group of faces, function is f(u,v)</li>
+<li>If geometry is edge or group of edges, function is f(t)</li>
+<li>If geometry is vertex or group of vertices, function is f()</li>
+<li>The function must return a double</li>
+</ul></li>