positionFraction property
double
get
positionFraction
Gtk value / (upper - page_size) inverted for thumb placement:
1.0 = live bottom (thumb at track bottom), 0.0 = history top.
Implementation
double get positionFraction {
if (historySize <= 0) return 1.0;
final value = (scrollOffsetLines / historySize).clamp(0.0, 1.0);
return 1.0 - value;
}