How to let a numerical field to be assigned preferrentially by user input?

I'm designing a GUI app using App-Designer, and below is what I want for two numerical fields, i.e., the min depth and max depth of a plot.

If a user does not input anything, the values will be automatifcally generated based on the data. The next time when the same button is clicked, it will use either the previously generated min and max values, or the user modified values. I do this so that a user can "zoom in" to a specific depth range for the plots.

Is this possible?

Answer 1

[Walter Roberson]

Just always fetch the current version of the field; if the user hasn't modified the values since the last time then they will be the same as they were. Initialize at appropriate times.