# API Changes for 3.0.1

`matplotlib.tight_layout.auto_adjust_subplotpars` can return `None` now
if the new subplotparams will collapse axes to zero width or height.
This prevents `tight_layout` from being executed. Similarly
`matplotlib.tight_layout.get_tight_layout_figure` will return None.

To improve import (startup) time, private modules are now imported
lazily. These modules are no longer available at these locations:

-   `matplotlib.backends.backend_agg._png`
-   `matplotlib.contour._contour`
-   `matplotlib.image._png`
-   `matplotlib.mathtext._png`
-   `matplotlib.testing.compare._png`
-   `matplotlib.texmanager._png`
-   `matplotlib.tri.triangulation._tri`
-   `matplotlib.tri.triangulation._qhull`
-   `matplotlib.tri.tricontour._tri`
-   `matplotlib.tri.trifinder._tri`