Configurable width for the navbar title and corner button.

[lucaboieru]

In my app I use not only icons, but also text for the corner buttons and something interesting happens. Here's a screenshot:

The title overlays the corner button. From my understanding that's because the title container has flex: 6 (here) the corners have flex: 1 (here). If, for example, I set the corner flex to 2 everything works as I want.
Could it be possible to make these rules configurable?

Thank you very much for the great work!

[charpeni]

We will consider this.

PRs are welcome :)

[davidLeonardi]

This is in progress in #83