FigureCanvas draw_idle skips redraw after Line2D set_data in GTK3Agg and TkAgg backends
Stale cache behavior in interactive backends Matplotlib's FigureCanvasBase relies on an internal _need_draw flag to decide whether draw_idle() should trigger a render pass. When a Line2D artist's data is updated via set_data() , the flag is not automatically set to True in several interactive backends, notably GTK3Agg and TkAgg. This causes draw_idle() to be
matplotlib