setSelectionMode method
Controls how the terminal behaves when the user selects a range of text. The default is SelectionMode.line. Setting this to SelectionMode.block enables block selection mode.
Implementation
void setSelectionMode(SelectionMode newSelectionMode) {
// If the new mode is the same as the old mode,
// nothing has to be changed.
if (_selectionMode == newSelectionMode) {
return;
}
// Set the new mode.
_selectionMode = newSelectionMode;
notifyListeners();
}