I knew this functionality existed, but I hadn't really put it to use until yesterday. It saved me a lot of time, so I just had to share. Here's the situation I found myself in:
LVS showed that I was missing vias to a small handful of my power-switch cells. Due to the structure of the cell, we had to make a modified copy of the LEF to get the exact via structures we wanted when we initially put in the power grid. I wasn't looking forward to swapping in a modified LEF, adding these few missing vias, and then swapping back. I wanted a quick way to just add the same kind of via as all the other connections had. Enter the "Add Via" widget:
When you click on this, you get a cursor that looks like a single via. The important next step is to press the F3 key to bring up the options form. It looks like this:
If you wanted to create a new via here, say a 4 x 6 array, you would use the Geometry option, which is the default the form comes up with. But, I already had a via that I wanted to use, and I knew the name of it. So I selected the ViaCell option and entered the name:
Then all I had to do was click in my design where I wanted the via to go. It snapped to the cell pin beautifully. So easy!