"Too few parameters for subcircuit type "half74hc74ee" (instance: xxu3)" error when using spice symbol with hidden pins in Sandbox V.2.1.1.
Create a spice symbol with hidden power pins (example: VDD and VSS pins in HALF74HC74EE);
Place it in schematic and connect it up;
Run sim;
Npgspice reports not enough connections to subckt:
`Too few parameters for subcircuit type "half74hc74ee" (instance: xxu3)`;
Netlist shows no connections to VDD and VSS pins;
Click on symbol and type **I**;
Tick `Hidden pins`;
Connect up hidden power pins,
Run sim;
Sim runs OK;
Netlist shows connections to VDD and VSS pins.
* Note: untick `Hidden pins` after tick `Hidden pins` does **not** hide pins again.
Examples:
<http://sandbox.easyeda.com/editor#id=eS0wqkd7p|h3s2ecaw5>
