color: Fix fallout from the GtkTemplate port
Correct a typoed variable name so that calibration works again, instead of crashing.
GLib-GObject-WARNING **: 15:52:50.561: invalid cast from 'GtkBox' to 'GtkEntry'
Correct a typoed variable name so that calibration works again, instead of crashing.
GLib-GObject-WARNING **: 15:52:50.561: invalid cast from 'GtkBox' to 'GtkEntry'