Plot X axis resizing

[devmnob]

When changing Bit Mode on the Levels Toolbar, the X axis will expand to accommodate a higher bit mode, however, if we change back to a lower Bit Mode it will not zoom back to accommodate.

[thocoo]

This is intended behavior. You don't want the histogram to scale when switching between the sigma's.
But I can make it scale when you choose one of the 'bit' settings.

[devmnob]

That will work for us, thank you