Brightness/Contrast min/max fields are not respected

Create a black float image 1000 x 1000
Run Process > Math Equation
Use this data for input to dialog: [y](x,), (x + y) / 1000
This makes a ramp 0 to 2 by thousandths
Now open B&C and set min to 0.001 and max to 0.008
Tabbing out of the fields will not use entered values but some calculated values instead.

This ticket based on an email from Michael Schmid

Migrated-From: http://trac.imagej.net/ticket/1809

Reproduce the issue by creating the 1000 × 1000 ramp with Process > Math Equation, then opening B&C and entering min 0.001 and max 0.008. Start at the B&C command and its min/max field handling; done means tabbing out preserves the entered values instead of replacing them with calculated values.

Written by the indexing model from the issue text.