create aux/ with some tutos

zUtil_Python/pydct/aux/useful.md

+* matplotlib interactive output capture
+
+```python
+out = widgets.Output()
+with out:
+    fig = plt.figure()
+```
+
+* `ipywidgets.AppLayout`
+
+```python
+widgets.AppLayout(
+    center=out,
+    footer=widgets.Button(icon='check'),
+    pane_heights=[0, 6, 1]
+)
+```
+
+* image stack with slider (pre-computed + update)
+
+```python
+plt.ioff()
+fig = plt.figure()
+plt.ion()
+im = plt.imshow(example_image_stack[0])
+
+def update(change):
+    im.set_data(example_image_stack[change['new']])
+    fig.canvas.draw_idle()
+    
+    
+slider = widgets.IntSlider(value=0, min=0, max=len(parameter)-1)
+slider.observe(update, names='value')
+widgets.VBox([slider, fig.canvas])
+```
+
+* debug `update(change)` function
+
+```python
+out = widgets.Output()
+@out.capture()
+def update(change):
+    with out:
+        if change['name'] == 'value':
+            im.set_data(example_image_stack[change['new']])
+            fig.canvas.draw_idle
+```
+
+or `Log Console (View > Show Log Console)`
+
+* output view
+
+on a cell `*click right*` > `Create New View for Output`
+
+* sidecar
+
+https://github.com/jupyter-widgets/jupyterlab-sidecar
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