Select two resistors that form a voltage divider and calculate output voltage or tune resistor values when output voltage is changed.

The script picks up exactly two resistors from the selection and presents a dialog box where the user can change values. The calculator will recalculate the resulting value upon changes. If the user clicks on "set & close", the script writes back resulting resistor values.

Note: +0 in fawk (and in awk) triggers a conversion to numeric value. This is used to make sure arrays are indexed with numbers and numeric widgets are loaded with numbers.

How to test:

- load the script
- draw a voltage dicider using two resistor
- name the resistor, make sure their name start with R
- select the two resistor, but no other resistor (selecting wires and non-R symbols is okay)
- invoke the script from menu or with hotkey {p s d}
- change resistor values and input voltages to see output voltage recalculated
- change output voltage to see the non-locked resistor value recalculated
- click "set & close" to copy back the new resistor value(s) to the drawing