Usage of the highlighter:
push into cell(s), select anything. All nets connected to a selected object will be highlighted in their full extent (up & down the hierarchy). Registering a technology and extract mode is easy (defaults are provided for layout-style extraction).
Promotion rules:
all wires which have some geometry intersecting the border (the interest rect) are promoted public. It is NOT possible to do the following rule (because it works only one level): If a property $IsPublic (with an atomic value being $TRUE or $FALSE) is attached to a piece of geometry, the promotion is done accordingly to the value of the "boolean".