René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Wait cursor may cause Tk to print _get_renderer.Done backtrace","articleBody":"## Bug report\r\n\r\n**Bug summary**\r\n\r\nI was looking at #11769, and apparently Gouraud shading was slow enough to trigger the wait cursor on the third figure. This printed out a backtrace, though the figures seems to be saved just fine.\r\n\r\n**Code for reproduction**\r\n\r\nSee #11769.\r\n\r\n**Actual outcome**\r\n\r\n```\r\n../mpl-tests/issue11769.py:23: MatplotlibDeprecationWarning: shading='flat' when X and Y have the same dimensions as C is deprecated since 3.3.  Either specify the corners of the quadrilaterals with X and Y, or pass shading='auto', 'nearest' or 'gouraud', or set rcParams['pcolor.shading'].  This will become an error two minor releases later.\r\n  plt.pcolormesh(x,y,map2,cmap='viridis',vmin=np.nanmin(map2),vmax=np.nanmax(map2))\r\n\r\nException in Tkinter callback\r\nTraceback (most recent call last):\r\n  File \"/var/container/conda/envs/mpl37/lib/python3.7/tkinter/__init__.py\", line 1705, in __call__\r\n    return self.func(*args)\r\n  File \"/var/container/conda/envs/mpl37/lib/python3.7/tkinter/__init__.py\", line 749, in callit\r\n    func(*args)\r\n  File \".../matplotlib/lib/matplotlib/backends/_backend_tk.py\", line 247, in idle_draw\r\n    self.draw()\r\n  File \".../matplotlib/lib/matplotlib/backends/backend_tkagg.py\", line 9, in draw\r\n    super().draw()\r\n  File \".../matplotlib/lib/matplotlib/backends/backend_agg.py\", line 409, in draw\r\n    self.figure.draw(self.renderer)\r\n  File \".../matplotlib/lib/matplotlib/backend_bases.py\", line 1546, in _draw\r\n    def _draw(renderer): raise Done(renderer)\r\nmatplotlib.backend_bases._get_renderer.\u003clocals\u003e.Done: \u003cmatplotlib.backends.backend_agg.RendererAgg object at 0x7f45c8946290\u003e\r\n```\r\n\r\n**Expected outcome**\r\n\r\nNo backtrace printed.\r\n\r\n**Matplotlib version**\r\n  * Operating system: Fedora 31\r\n  * Matplotlib version: master 52761deb15b9c0aca05112befcdefce5cea0a2ad\r\n  * Matplotlib backend (`print(matplotlib.get_backend())`): TkAgg\r\n  * Python version: 3.7.6","author":{"url":"https://github.com/QuLogic","@type":"Person","name":"QuLogic"},"datePublished":"2020-08-05T22:28:25.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":3},"url":"https://github.com/18186/matplotlib/issues/18186"}