3. Navigation inside the plot

Now you see the stratigraphic diagram (by default) centered at the top of the graphical user interface. Additionally you find a separate window to it’s right with a magnified version of the diagram. It follows your mouse movements inside the diagram and shows you a magnified version of it.

To navigate inside the plot, you can use the default navigation toolbar that is provided by matplotlib

Especially the Pan/Zoom button and the zoom-to-rectangle button are of interest for you. You can enable and disable them by clicking on the corresponding button in the toolbar.

The matplotlib docs provide further guidance:

The Pan/Zoom button

This button has two modes: pan and zoom. Click the toolbar button to activate panning and zooming, then put your mouse somewhere over an axes. Press the left mouse button and hold it to pan the figure, dragging it to a new position. When you release it, the data under the point where you pressed will be moved to the point where you released. If you press ‘x’ or ‘y’ while panning the motion will be constrained to the x or y axis, respectively. Press the right mouse button to zoom, dragging it to a new position. The x axis will be zoomed in proportionately to the rightward movement and zoomed out proportionately to the leftward movement. The same is true for the y axis and up/down motions. The point under your mouse when you begin the zoom remains stationary, allowing you to zoom in or out around that point as much as you wish. You can use the modifier keys ‘x’, ‘y’ or ‘CONTROL’ to constrain the zoom to the x axis, the y axis, or aspect ratio preserve, respectively.

With polar plots, the pan and zoom functionality behaves differently. The radius axis labels can be dragged using the left mouse button. The radius scale can be zoomed in and out using the right mouse button.

The Zoom-to-rectangle button

Click this toolbar button to activate this mode. Put your mouse somewhere over an axes and press a mouse button. Define a rectangular region by dragging the mouse while holding the button to a new location. When using the left mouse button, the axes view limits will be zoomed to the defined region. When using the right mouse button, the axes view limits will be zoomed out, placing the original axes in the defined region.

More information can be found in the matplotlib documentation: https://matplotlib.org/users/navigation_toolbar.html