View - Mesh Type toggles the display between the current density plot and the meshing plot which shows the mesh type being used in your circuit. Each mesh type is assigned a different color which is displayed in a legend on the left side of the current density viewer. The colors assigned to each mesh type can be changed in the View Options Dialog Box.
There are three different types of mesh: standard (staircase), conformal, and GLG. GLG is the metal used to model components and co-calibrated ports. Please note that View - GLG Metal must be selected for the GLG metal to appear in the meshing plot.
To view the Current Density plot of your circuit, you must turn this option off.